Rework the end screen figures, mode picker, corners and race view

End screen
- Every figure is now a dim label directly over its value, the two centred on
  each other, grouped by what they qualify: RAW and PB under WPM, ERR and
  CONSISTENCY under ACC, KEYSTROKES and CHARACTERS either side of TIME. The
  row is a grid so TIME sits on the graph's exact centre line rather than
  drifting with its neighbours' widths.
- Errors go back onto the wpm line. Their own y axis implied a magnitude a
  mistake does not have; what matters is when one happened.
- Graph hover reads "wpm ... raw ... time" - the figures first, the second
  they happened in as the qualifier.

Mode picker
- Opens from the Single Player button itself, and choosing a mode starts it:
  picking what to type and starting it are one action. The control has now
  been a chevron notched into that button, a caption between the two buttons,
  a pill above them and a chip row below them; as the button's own menu it
  needs no separate real estate at all.

Corners
- Settings and Store move to the bottom-left. The top-left is the wordmark's
  alone.
- The global racer count is gone from the home screen - it is not something
  you can act on there. The Friends control carries "N online" instead, which
  is.
- Presence: users gain a last_seen column, touched at most once a minute per
  active user on any authenticated request, and the friends list reports who
  has been seen inside a five-minute window.

Multiplayer race view
- The standings move to the middle of the screen, the space the end screen's
  graph occupies, and now include your own row rather than opponents only.
  Pinned to the top-left corner they put what you are racing against in your
  peripheral vision and left out the one bar you most need to see.

Programming mode
- Snippets carry an explanation of what the code does. Shown under the passage
  while you type in single player; in multiplayer that space belongs to the
  standings, so it waits for the end screen, where it appears either way.

1 files changed, 557 insertions, 531 deletions

diff --git a/texts.json b/texts.json
index 0aef950..a618268 100644
--- a/texts.json
+++ b/texts.json
@@ -1,177 +1,184 @@
 [
   {
-    "category": "history",
-    "content": "The Cold War divided much of the world into two opposing blocs for nearly half a century, one aligned with the United States and the other with the Soviet Union.",
-    "attribution": "History"
+    "category": "technology",
+    "content": "The transistor, invented in 1947, replaced bulky vacuum tubes and became the foundational building block of nearly every modern electronic device.",
+    "attribution": "Technology"
   },
   {
-    "category": "philosophy",
-    "content": "Existentialism explores questions about individual freedom, choice, and meaning, arguing that people must create their own purpose in a universe that does not provide one automatically.",
-    "attribution": "Philosophy"
+    "category": "programming",
+    "content": "public static void main(String[] args) { System.out.println(\"ready\"); }",
+    "attribution": "Java",
+    "language": "clike",
+    "explanation": "Java's entry point. The signature is fixed: static so it runs without an instance, and taking the command-line arguments."
   },
   {
-    "category": "business",
-    "content": "The man who dies rich, dies disgraced.",
-    "attribution": "Andrew Carnegie"
+    "category": "science",
+    "content": "Water is one of the few substances that becomes less dense as it freezes, which is why ice floats on top of liquid water instead of sinking to the bottom.",
+    "attribution": "Science"
   },
   {
-    "category": "movies",
-    "content": "Stop motion animation creates the illusion of movement by photographing physical objects one frame at a time and repositioning them slightly between each shot.",
-    "attribution": "Film"
+    "category": "programming",
+    "content": "impl Display for Token { fn fmt(&self, f: &mut Formatter) -> Result { write!(f, \"{}\", self.0) } }",
+    "attribution": "Rust",
+    "language": "rust",
+    "explanation": "Implementing Display is what makes a type usable in {}. self.0 is the first field of a tuple struct."
   },
   {
-    "category": "technology",
-    "content": "A blockchain is a distributed ledger that records transactions across many computers, making it difficult to alter any single record without changing every subsequent block.",
-    "attribution": "Technology"
+    "category": "philosophy",
+    "content": "I think, therefore I am.",
+    "attribution": "Rene Descartes, Discourse on the Method"
   },
   {
-    "category": "nature",
-    "content": "Bees pollinate roughly a third of the crops humans rely on for food, making them essential to global agriculture despite their small size.",
-    "attribution": "Nature"
+    "category": "quotes",
+    "content": "The only limit to our realization of tomorrow is our doubts of today.",
+    "attribution": "Franklin D. Roosevelt"
   },
   {
-    "category": "business",
-    "content": "A balance sheet summarizes what a company owns and owes at a single point in time, split into assets, liabilities, and shareholders' equity.",
-    "attribution": "Business"
+    "category": "quotes",
+    "content": "It always seems impossible until it's done.",
+    "attribution": "Nelson Mandela"
+  },
+  {
+    "category": "quotes",
+    "content": "Failure is impossible.",
+    "attribution": "Susan B. Anthony"
   },
   {
     "category": "history",
-    "content": "The Industrial Revolution transformed economies across Europe and North America during the eighteenth and nineteenth centuries, shifting production from hand tools to machines.",
+    "content": "The Roman Empire at its height stretched from Britain in the north to Egypt in the south, connected by a vast network of roads that still exist in parts of Europe today.",
     "attribution": "History"
   },
   {
     "category": "literature",
-    "content": "In my younger and more vulnerable years my father gave me some advice that I've been turning over in my mind ever since. Whenever you feel like criticizing anyone, he told me, just remember that all the people in this world haven't had the advantages that you've had.",
-    "attribution": "F. Scott Fitzgerald, The Great Gatsby"
-  },
-  {
-    "category": "movies",
-    "content": "Method acting, popularized in the mid twentieth century, encourages performers to draw on personal memories and emotions to portray a character as realistically as possible.",
-    "attribution": "Film"
-  },
-  {
-    "category": "quotes",
-    "content": "Whatever you are, be a good one.",
-    "attribution": "Abraham Lincoln"
+    "content": "It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness.",
+    "attribution": "Charles Dickens, A Tale of Two Cities"
   },
   {
     "category": "general",
-    "content": "A day on Venus is longer than its year. The planet rotates so slowly on its axis that it takes longer to spin around once than it does to complete an entire orbit around the sun.",
+    "content": "Sharks existed long before trees. Fossil evidence suggests that sharks have been swimming in the oceans for more than four hundred million years, while the earliest trees did not appear until tens of millions of years later.",
     "attribution": "General knowledge"
   },
   {
-    "category": "quotes",
-    "content": "If there is no struggle, there is no progress. Those who profess to favor freedom, and yet depreciate agitation, are men who want crops without plowing up the ground.",
-    "attribution": "Frederick Douglass"
+    "category": "nature",
+    "content": "The Amazon rainforest is home to an estimated ten percent of all known species on Earth, making it one of the most biodiverse regions on the planet.",
+    "attribution": "Nature"
   },
   {
-    "category": "programming",
-    "content": "def fib(n): return n if n < 2 else fib(n - 1) + fib(n - 2)",
-    "attribution": "Python",
-    "language": "python"
+    "category": "movies",
+    "content": "A film's runtime is typically decided during editing, where an editor works with hours of raw footage to shape a coherent story within a manageable length.",
+    "attribution": "Film"
   },
   {
-    "category": "general",
-    "content": "The Great Wall of China was not built all at once. It was constructed and extended over many centuries by different dynasties, each adding new sections and rebuilding older ones to defend against invasions from the north.",
-    "attribution": "General knowledge"
+    "category": "science",
+    "content": "Evolution by natural selection describes how organisms with traits better suited to their environment tend to survive and reproduce more successfully, gradually shaping a population over many generations.",
+    "attribution": "Science, after Charles Darwin"
+  },
+  {
+    "category": "business",
+    "content": "Branding is the practice of shaping how customers perceive a company, going beyond a logo to include tone, values, and the overall experience of using a product.",
+    "attribution": "Business"
   },
   {
     "category": "programming",
-    "content": "struct node { int value; struct node *next; };",
-    "attribution": "C",
-    "language": "clike"
+    "content": "let mut counts: HashMap<String, usize> = HashMap::new();",
+    "attribution": "Rust",
+    "language": "rust",
+    "explanation": "mut because inserting mutates it. The type annotation is needed here since nothing yet tells the compiler what it holds."
   },
   {
-    "category": "general",
-    "content": "The Pacific Ocean covers more of the planet than all the continents combined. It stretches from the icy waters near Antarctica to the Arctic Circle, and its deepest point, the Mariana Trench, plunges nearly eleven kilometers below the surface.",
-    "attribution": "General knowledge"
+    "category": "business",
+    "content": "Henry Ford, founder of the Ford Motor Company, is credited with popularizing the moving assembly line, which dramatically reduced the time needed to build an automobile.",
+    "attribution": "History of Business"
   },
   {
-    "category": "science",
-    "content": "Marie Curie remains the only person to win Nobel Prizes in two different sciences, physics and chemistry, for her pioneering research into radioactivity.",
-    "attribution": "Science"
+    "category": "literature",
+    "content": "All we have to decide is what to do with the time that is given us.",
+    "attribution": "J.R.R. Tolkien, The Fellowship of the Ring"
   },
   {
     "category": "literature",
-    "content": "Call me Ishmael. Some years ago, never mind how long precisely, having little or no money in my purse, and nothing particular to interest me on shore, I thought I would sail about a little and see the watery part of the world.",
-    "attribution": "Herman Melville, Moby-Dick"
+    "content": "Mr. Sherlock Holmes, who was usually very late in the mornings, save upon those not infrequent occasions when he was up all night, was seated at the breakfast table.",
+    "attribution": "Arthur Conan Doyle, The Hound of the Baskervilles"
   },
   {
-    "category": "technology",
-    "content": "A virtual private network encrypts a device's internet connection, helping to protect data from being intercepted while it travels over a public or untrusted network.",
-    "attribution": "Technology"
+    "category": "literature",
+    "content": "The year 1866 was signalised by a remarkable incident, a mysterious and inexplicable phenomenon, which doubtless no one has yet forgotten. Ships had met with a huge thing, a long object, spindle-shaped, and at times phosphorescent.",
+    "attribution": "Jules Verne, Twenty Thousand Leagues Under the Sea"
   },
   {
-    "category": "philosophy",
-    "content": "It is not that we have a short time to live, but that we waste a lot of it.",
-    "attribution": "Seneca, On the Shortness of Life"
+    "category": "literature",
+    "content": "A throng of bearded men, in sad-colored garments and gray, steeple-crowned hats, intermixed with women, some wearing hoods, and others bareheaded, was assembled in front of a wooden edifice.",
+    "attribution": "Nathaniel Hawthorne, The Scarlet Letter"
   },
   {
-    "category": "nature",
-    "content": "Deserts are defined by low precipitation rather than temperature, which is why some of the coldest places on Earth, including parts of Antarctica, are technically deserts.",
-    "attribution": "Nature"
+    "category": "science",
+    "content": "The speed of light in a vacuum is approximately two hundred ninety nine thousand, seven hundred ninety two kilometers per second, and nothing with mass can reach or exceed it.",
+    "attribution": "Science"
   },
   {
     "category": "science",
-    "content": "Sound travels as a wave of pressure through a medium such as air or water, and it cannot travel through the vacuum of space, since there are no particles to carry the vibration.",
+    "content": "Photosynthesis is the process by which plants convert light energy into chemical energy, using carbon dioxide and water to produce glucose and release oxygen as a byproduct.",
     "attribution": "Science"
   },
   {
-    "category": "nature",
-    "content": "The Amazon rainforest is home to an estimated ten percent of all known species on Earth, making it one of the most biodiverse regions on the planet.",
-    "attribution": "Nature"
+    "category": "history",
+    "content": "The invention of the wheel around 3500 BCE is considered one of the most important technological breakthroughs in human history, transforming transportation and trade.",
+    "attribution": "History"
   },
   {
-    "category": "programming",
-    "content": "with open('data.csv', encoding='utf-8') as f: rows = [line.split(',') for line in f]",
-    "attribution": "Python",
-    "language": "python"
+    "category": "movies",
+    "content": "Citizen Kane, released in 1941, is frequently cited by critics and filmmakers as one of the greatest films ever made, praised for its innovative camera work and narrative structure.",
+    "attribution": "Film"
   },
   {
-    "category": "quotes",
-    "content": "The only limit to our realization of tomorrow is our doubts of today.",
-    "attribution": "Franklin D. Roosevelt"
+    "category": "science",
+    "content": "Sound travels as a wave of pressure through a medium such as air or water, and it cannot travel through the vacuum of space, since there are no particles to carry the vibration.",
+    "attribution": "Science"
   },
   {
     "category": "quotes",
-    "content": "Genius is one percent inspiration and ninety-nine percent perspiration.",
-    "attribution": "Thomas Edison"
+    "content": "Success is to be measured not so much by the position that one has reached in life as by the obstacles which he has overcome while trying to succeed.",
+    "attribution": "Booker T. Washington"
+  },
+  {
+    "category": "literature",
+    "content": "There was no possibility of taking a walk that day. We had been wandering, indeed, in the leafless shrubbery an hour in the morning, but since dinner the cold winter wind had brought with it clouds so sombre, and a rain so penetrating.",
+    "attribution": "Charlotte Bronte, Jane Eyre"
+  },
+  {
+    "category": "literature",
+    "content": "Not all those who wander are lost.",
+    "attribution": "J.R.R. Tolkien"
   },
   {
     "category": "technology",
-    "content": "Cloud computing allows businesses and individuals to rent computing power and storage over the internet instead of maintaining their own physical servers.",
+    "content": "A central processing unit executes the instructions of a computer program by performing basic arithmetic, logic, and input and output operations.",
     "attribution": "Technology"
   },
   {
-    "category": "movies",
-    "content": "Silent films relied on live musicians and title cards to convey dialogue and emotion, since synchronized sound was not introduced into feature films until the late 1920s.",
-    "attribution": "Film"
+    "category": "nature",
+    "content": "In every walk with nature one receives far more than he seeks.",
+    "attribution": "John Muir"
   },
   {
     "category": "literature",
-    "content": "It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness.",
-    "attribution": "Charles Dickens, A Tale of Two Cities"
-  },
-  {
-    "category": "quotes",
-    "content": "It always seems impossible until it's done.",
-    "attribution": "Nelson Mandela"
+    "content": "The Nellie, a cruising yawl, swung to her anchor without a flutter of the sails, and was at rest. The flood had made, the wind was nearly calm, and being bound down the river, the only thing for it was to come to and wait for the turn of the tide.",
+    "attribution": "Joseph Conrad, Heart of Darkness"
   },
   {
-    "category": "general",
-    "content": "Bamboo is one of the fastest growing plants on Earth. Some species can grow nearly a meter in a single day under the right conditions, which is why it is used so widely in construction and manufacturing across Asia.",
-    "attribution": "General knowledge"
+    "category": "technology",
+    "content": "A firewall monitors and controls incoming and outgoing network traffic based on predetermined security rules, acting as a barrier between a trusted network and an untrusted one.",
+    "attribution": "Technology"
   },
   {
-    "category": "programming",
-    "content": "const unique = [...new Set(values)].sort((a, b) => a - b);",
-    "attribution": "JavaScript",
-    "language": "javascript"
+    "category": "quotes",
+    "content": "Whatever you are, be a good one.",
+    "attribution": "Abraham Lincoln"
   },
   {
-    "category": "nature",
-    "content": "The Sahara Desert was once a green landscape with lakes and grasslands, before a shift in the Earth's orbit altered rainfall patterns thousands of years ago.",
-    "attribution": "Nature"
+    "category": "philosophy",
+    "content": "A journey of a thousand miles begins with a single step.",
+    "attribution": "Lao Tzu, Tao Te Ching"
   },
   {
     "category": "movies",
@@ -180,210 +187,207 @@
   },
   {
     "category": "general",
-    "content": "The invention of the printing press in the fifteenth century transformed how knowledge spread across Europe. Books that once took months to copy by hand could suddenly be reproduced by the hundreds, making literacy far more accessible.",
+    "content": "Bamboo is one of the fastest growing plants on Earth. Some species can grow nearly a meter in a single day under the right conditions, which is why it is used so widely in construction and manufacturing across Asia.",
     "attribution": "General knowledge"
   },
   {
-    "category": "science",
-    "content": "Genetics research has shown that humans share about ninety-nine percent of their DNA with chimpanzees, the closest living relative to our species.",
-    "attribution": "Science"
+    "category": "programming",
+    "content": "pub struct Point { pub x: f64, pub y: f64 }",
+    "attribution": "Rust",
+    "language": "rust",
+    "explanation": "Fields are private by default in Rust, so each one needs its own pub - making the struct public does not publish its contents."
   },
   {
-    "category": "programming",
-    "content": "if err != nil { return fmt.Errorf(\"read config: %w\", err) }",
-    "attribution": "Go",
-    "language": "clike"
+    "category": "nature",
+    "content": "Migratory birds can travel thousands of miles between breeding and wintering grounds, navigating using the sun, stars, and the Earth's magnetic field.",
+    "attribution": "Nature"
   },
   {
-    "category": "history",
-    "content": "The fall of the Berlin Wall in 1989 marked a turning point in the Cold War, as East and West Germany moved toward reunification the following year.",
-    "attribution": "History"
+    "category": "nature",
+    "content": "The world is big and I want to have a good look at it before it gets dark.",
+    "attribution": "John Muir"
   },
   {
-    "category": "business",
-    "content": "The purpose of a business is to create and keep a customer.",
-    "attribution": "Peter Drucker"
+    "category": "literature",
+    "content": "It was the best of times, it was the worst of times.",
+    "attribution": "Charles Dickens, A Tale of Two Cities"
   },
   {
     "category": "technology",
-    "content": "Open source software is released with its source code publicly available, allowing anyone to view, modify, and distribute it under the terms of its license.",
+    "content": "Artificial intelligence refers to computer systems designed to perform tasks that normally require human intelligence, such as recognizing speech, images, or patterns in data.",
     "attribution": "Technology"
   },
   {
     "category": "business",
-    "content": "A startup's burn rate measures how quickly it spends its available cash, an important number for founders trying to plan how long the company can operate before running out of money.",
+    "content": "Supply and demand describes how the price of a good tends to rise when demand exceeds supply, and fall when supply exceeds demand.",
     "attribution": "Business"
   },
   {
-    "category": "philosophy",
-    "content": "I think, therefore I am.",
-    "attribution": "Rene Descartes, Discourse on the Method"
-  },
-  {
-    "category": "programming",
-    "content": "export PATH=\"$HOME/.local/bin:$PATH\" && command -v rg >/dev/null || echo missing",
-    "attribution": "Shell",
-    "language": "shell"
+    "category": "general",
+    "content": "The quick brown fox jumps over the lazy dog.",
+    "attribution": "Traditional pangram"
   },
   {
-    "category": "programming",
-    "content": "if (typeof value !== 'string' || value.length === 0) { return null; }",
-    "attribution": "JavaScript",
-    "language": "javascript"
+    "category": "movies",
+    "content": "The Academy Awards, commonly known as the Oscars, have been presented annually since 1929 to honor achievements in the film industry.",
+    "attribution": "Film"
   },
   {
-    "category": "philosophy",
-    "content": "Every new beginning comes from some other beginning's end.",
-    "attribution": "Seneca, Letters from a Stoic"
+    "category": "general",
+    "content": "Venus is the hottest planet in the solar system, even though Mercury sits closer to the sun. A thick blanket of carbon dioxide traps heat at the surface.",
+    "attribution": "General knowledge"
   },
   {
     "category": "history",
-    "content": "Ancient Egyptian civilization flourished along the Nile River for thousands of years, leaving behind monuments such as the pyramids of Giza and the temples of Luxor.",
+    "content": "The Wright brothers achieved the first powered, controlled flight in 1903 near Kitty Hawk, North Carolina, a flight that lasted only twelve seconds.",
     "attribution": "History"
   },
   {
-    "category": "literature",
-    "content": "To Sherlock Holmes she is always the woman. I have seldom heard him mention her under any other name. In his eyes she eclipses and predominates the whole of her sex.",
-    "attribution": "Arthur Conan Doyle, A Scandal in Bohemia"
-  },
-  {
-    "category": "literature",
-    "content": "My father's family name being Pirrip, and my Christian name Philip, my infant tongue could make of both names nothing longer or more explicit than Pip. So, I called myself Pip, and came to be called Pip.",
-    "attribution": "Charles Dickens, Great Expectations"
-  },
-  {
-    "category": "literature",
-    "content": "It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife. However little known the feelings or views of such a man may be on his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding families.",
-    "attribution": "Jane Austen, Pride and Prejudice"
-  },
-  {
     "category": "technology",
-    "content": "The World Wide Web was invented by Tim Berners-Lee in 1989 as a way to share documents over the internet using hyperlinks.",
+    "content": "Fiber optic cables transmit data as pulses of light through thin strands of glass, allowing information to travel at extremely high speeds over long distances.",
     "attribution": "Technology"
   },
   {
-    "category": "movies",
-    "content": "The highest grossing films of all time are dominated by franchises built around superheroes, fantasy worlds, and long running science fiction universes.",
-    "attribution": "Film"
-  },
-  {
     "category": "programming",
-    "content": "match result { Ok(v) => println!(\"{v}\"), Err(e) => eprintln!(\"error: {e}\") }",
-    "attribution": "Rust",
-    "language": "rust"
+    "content": "if err != nil { return fmt.Errorf(\"read config: %w\", err) }",
+    "attribution": "Go",
+    "language": "clike",
+    "explanation": "Go's error convention. %w wraps the original so errors.Is and errors.As can still see it further up."
   },
   {
-    "category": "programming",
-    "content": "let total: i64 = values.iter().filter(|v| **v > 0).sum();",
-    "attribution": "Rust",
-    "language": "rust"
+    "category": "business",
+    "content": "A balance sheet summarizes what a company owns and owes at a single point in time, split into assets, liabilities, and shareholders' equity.",
+    "attribution": "Business"
   },
   {
-    "category": "science",
-    "content": "Water is one of the few substances that becomes less dense as it freezes, which is why ice floats on top of liquid water instead of sinking to the bottom.",
-    "attribution": "Science"
+    "category": "programming",
+    "content": "export PATH=\"$HOME/.local/bin:$PATH\" && command -v rg >/dev/null || echo missing",
+    "attribution": "Shell",
+    "language": "shell",
+    "explanation": "Prepending puts your own binaries ahead of the system ones. command -v is the portable test for whether something is installed."
   },
   {
     "category": "movies",
-    "content": "The Academy Awards, commonly known as the Oscars, have been presented annually since 1929 to honor achievements in the film industry.",
+    "content": "The first feature length narrative film, The Story of the Kelly Gang, was made in Australia in 1906 and ran for about an hour.",
     "attribution": "Film"
   },
   {
-    "category": "literature",
-    "content": "All we have to decide is what to do with the time that is given us.",
-    "attribution": "J.R.R. Tolkien, The Fellowship of the Ring"
-  },
-  {
-    "category": "business",
-    "content": "Market research helps a business understand its customers' needs and preferences before committing resources to a new product or service.",
-    "attribution": "Business"
+    "category": "nature",
+    "content": "The Sahara Desert was once a green landscape with lakes and grasslands, before a shift in the Earth's orbit altered rainfall patterns thousands of years ago.",
+    "attribution": "Nature"
   },
   {
     "category": "general",
-    "content": "A group of flamingos is called a flamboyance. The birds get their pink color from the pigments in the shrimp and algae they eat.",
+    "content": "Antarctica is technically the largest desert on the planet. Despite being covered in ice, it receives very little precipitation each year, which is the defining characteristic of a desert rather than temperature alone.",
     "attribution": "General knowledge"
   },
   {
+    "category": "history",
+    "content": "The signing of the Magna Carta in 1215 limited the power of the English king and established the principle that even a monarch was subject to the law.",
+    "attribution": "History"
+  },
+  {
     "category": "programming",
-    "content": "for f in *.log; do gzip -9 \"$f\" && echo \"packed $f\"; done",
-    "attribution": "Shell",
-    "language": "shell"
+    "content": "const { id, name = 'anonymous', ...rest } = await request.json();",
+    "attribution": "JavaScript",
+    "language": "javascript",
+    "explanation": "Destructuring with a default and a rest property. The default applies only when the value is undefined, not when it is null."
   },
   {
-    "category": "business",
-    "content": "Customer obsession, rather than competitor focus, is the surest path to long term success.",
-    "attribution": "Jeff Bezos"
+    "category": "history",
+    "content": "The Industrial Revolution transformed economies across Europe and North America during the eighteenth and nineteenth centuries, shifting production from hand tools to machines.",
+    "attribution": "History"
   },
   {
-    "category": "technology",
-    "content": "A central processing unit executes the instructions of a computer program by performing basic arithmetic, logic, and input and output operations.",
-    "attribution": "Technology"
+    "category": "general",
+    "content": "The Great Wall of China was not built all at once. It was constructed and extended over many centuries by different dynasties, each adding new sections and rebuilding older ones to defend against invasions from the north.",
+    "attribution": "General knowledge"
+  },
+  {
+    "category": "history",
+    "content": "The Cold War divided much of the world into two opposing blocs for nearly half a century, one aligned with the United States and the other with the Soviet Union.",
+    "attribution": "History"
   },
   {
     "category": "science",
-    "content": "The speed of light in a vacuum is approximately two hundred ninety nine thousand, seven hundred ninety two kilometers per second, and nothing with mass can reach or exceed it.",
+    "content": "Vaccines work by training the immune system to recognize a weakened or partial version of a pathogen, so the body can respond quickly if it ever encounters the real threat.",
     "attribution": "Science"
   },
   {
     "category": "science",
-    "content": "The human body contains roughly thirty seven trillion cells, each one specialized to carry out one of hundreds of different jobs inside the body.",
+    "content": "A black hole forms when a massive star collapses under its own gravity, packing so much mass into so small a space that not even light can escape its pull.",
     "attribution": "Science"
   },
   {
-    "category": "nature",
-    "content": "In every walk with nature one receives far more than he seeks.",
-    "attribution": "John Muir"
+    "category": "programming",
+    "content": "for i, v := range items { fmt.Printf(\"%d: %v\\n\", i, v) }",
+    "attribution": "Go",
+    "language": "clike",
+    "explanation": "range yields index and value. In Go before 1.22 the loop variable was reused each iteration, which surprised anyone capturing it in a closure."
   },
   {
-    "category": "business",
-    "content": "Branding is the practice of shaping how customers perceive a company, going beyond a logo to include tone, values, and the overall experience of using a product.",
-    "attribution": "Business"
+    "category": "quotes",
+    "content": "Genius is one percent inspiration and ninety-nine percent perspiration.",
+    "attribution": "Thomas Edison"
   },
   {
-    "category": "technology",
-    "content": "The transistor, invented in 1947, replaced bulky vacuum tubes and became the foundational building block of nearly every modern electronic device.",
-    "attribution": "Technology"
+    "category": "general",
+    "content": "The Pacific Ocean covers more of the planet than all the continents combined. It stretches from the icy waters near Antarctica to the Arctic Circle, and its deepest point, the Mariana Trench, plunges nearly eleven kilometers below the surface.",
+    "attribution": "General knowledge"
   },
   {
-    "category": "programming",
-    "content": "pub struct Point { pub x: f64, pub y: f64 }",
-    "attribution": "Rust",
-    "language": "rust"
+    "category": "philosophy",
+    "content": "It's not what happens to you, but how you react to it that matters.",
+    "attribution": "Epictetus"
   },
   {
-    "category": "general",
-    "content": "Octopuses have three hearts and blue blood. Two of the hearts pump blood to the gills, while the third circulates it to the rest of the body, and the blue color comes from a copper-based protein instead of iron.",
-    "attribution": "General knowledge"
+    "category": "literature",
+    "content": "I read that every known superstition in the world is gathered into the horseshoe of the Carpathians, as if it were the centre of some sort of imaginative whirlpool, and it made me uneasy in a way I could not explain.",
+    "attribution": "Bram Stoker, Dracula"
   },
   {
-    "category": "general",
-    "content": "The Amazon rainforest produces roughly twenty percent of the oxygen found in the planet's atmosphere, earning it the nickname the lungs of the Earth.",
-    "attribution": "General knowledge"
+    "category": "programming",
+    "content": "const unique = [...new Set(values)].sort((a, b) => a - b);",
+    "attribution": "JavaScript",
+    "language": "javascript",
+    "explanation": "A Set discards duplicates. Spreading it back to an array allows sorting; the comparator is required or numbers sort as text."
+  },
+  {
+    "category": "technology",
+    "content": "Quantum computing uses the principles of quantum mechanics to process information in ways that classical computers cannot, potentially solving certain problems far faster.",
+    "attribution": "Technology"
   },
   {
     "category": "quotes",
-    "content": "If I have seen further, it is by standing on the shoulders of giants.",
-    "attribution": "Isaac Newton"
+    "content": "Our greatest glory is not in never falling, but in rising every time we fall.",
+    "attribution": "Confucius"
   },
   {
     "category": "general",
-    "content": "A single bolt of lightning can heat the surrounding air to temperatures hotter than the surface of the sun. The rapid expansion of that superheated air is what produces the crack of thunder we hear moments later.",
+    "content": "The human brain generates enough electricity to power a small light bulb. Billions of neurons firing electrical signals at once produce roughly the same wattage as a dim household lamp.",
     "attribution": "General knowledge"
   },
   {
-    "category": "business",
-    "content": "Henry Ford, founder of the Ford Motor Company, is credited with popularizing the moving assembly line, which dramatically reduced the time needed to build an automobile.",
-    "attribution": "History of Business"
+    "category": "literature",
+    "content": "Christmas won't be Christmas without any presents, grumbled Jo, lying on the rug. It's so dreadful to be poor, sighed Meg, looking down at her old dress.",
+    "attribution": "Louisa May Alcott, Little Women"
   },
   {
-    "category": "business",
-    "content": "A merger combines two companies into one, while an acquisition occurs when one company purchases and absorbs another, though the two terms are often used loosely in everyday conversation.",
-    "attribution": "Business"
+    "category": "history",
+    "content": "The Silk Road was not a single road but a network of trade routes connecting China to the Mediterranean, carrying silk, spices, and ideas across the ancient world.",
+    "attribution": "History"
   },
   {
-    "category": "movies",
-    "content": "The special effects in the original Star Wars trilogy were largely achieved with physical models and practical effects, long before computer generated imagery became common.",
-    "attribution": "Film"
+    "category": "literature",
+    "content": "Call me Ishmael. Some years ago, never mind how long precisely, having little or no money in my purse, and nothing particular to interest me on shore, I thought I would sail about a little and see the watery part of the world.",
+    "attribution": "Herman Melville, Moby-Dick"
+  },
+  {
+    "category": "programming",
+    "content": "export async function load(url) { const res = await fetch(url); return res.json(); }",
+    "attribution": "JavaScript",
+    "language": "javascript",
+    "explanation": "fetch resolves as soon as headers arrive, so .json() is a second await for the body. It does not throw on a 404 - check res.ok."
   },
   {
     "category": "history",
@@ -391,118 +395,100 @@
     "attribution": "History"
   },
   {
-    "category": "science",
-    "content": "Vaccines work by training the immune system to recognize a weakened or partial version of a pathogen, so the body can respond quickly if it ever encounters the real threat.",
-    "attribution": "Science"
+    "category": "quotes",
+    "content": "Stay hungry, stay foolish.",
+    "attribution": "Steve Jobs"
   },
   {
     "category": "nature",
-    "content": "Wolves live and hunt in structured packs, usually led by a breeding pair, and communicate through howls that can be heard for several kilometers.",
+    "content": "Bees pollinate roughly a third of the crops humans rely on for food, making them essential to global agriculture despite their small size.",
     "attribution": "Nature"
   },
   {
+    "category": "quotes",
+    "content": "It is not the critic who counts; not the man who points out how the strong man stumbles. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood.",
+    "attribution": "Theodore Roosevelt, Citizenship in a Republic"
+  },
+  {
     "category": "business",
-    "content": "Supply and demand describes how the price of a good tends to rise when demand exceeds supply, and fall when supply exceeds demand.",
+    "content": "Market research helps a business understand its customers' needs and preferences before committing resources to a new product or service.",
     "attribution": "Business"
   },
   {
     "category": "nature",
-    "content": "The deepest part of the ocean, the Mariana Trench, plunges nearly eleven kilometers below the surface, deeper than Mount Everest is tall.",
+    "content": "A single mature tree can absorb around twenty two kilograms of carbon dioxide per year, making forests an important part of regulating the planet's climate.",
     "attribution": "Nature"
   },
   {
-    "category": "literature",
-    "content": "I read that every known superstition in the world is gathered into the horseshoe of the Carpathians, as if it were the centre of some sort of imaginative whirlpool, and it made me uneasy in a way I could not explain.",
-    "attribution": "Bram Stoker, Dracula"
-  },
-  {
-    "category": "general",
-    "content": "The human brain generates enough electricity to power a small light bulb. Billions of neurons firing electrical signals at once produce roughly the same wattage as a dim household lamp.",
-    "attribution": "General knowledge"
-  },
-  {
-    "category": "quotes",
-    "content": "Four score and seven years ago our fathers brought forth on this continent a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.",
-    "attribution": "Abraham Lincoln, The Gettysburg Address"
-  },
-  {
-    "category": "programming",
-    "content": "export async function load(url) { const res = await fetch(url); return res.json(); }",
-    "attribution": "JavaScript",
-    "language": "javascript"
-  },
-  {
     "category": "science",
-    "content": "Mitochondria convert nutrients into a usable form of energy for the cell, which is why biology textbooks often call them the powerhouse of the cell.",
+    "content": "The theory of plate tectonics explains how the Earth's outer shell is broken into large plates that slowly drift over the mantle, causing earthquakes, volcanoes, and mountain formation.",
     "attribution": "Science"
   },
   {
-    "category": "history",
-    "content": "The Wright brothers achieved the first powered, controlled flight in 1903 near Kitty Hawk, North Carolina, a flight that lasted only twelve seconds.",
-    "attribution": "History"
-  },
-  {
-    "category": "literature",
-    "content": "It was the best of times, it was the worst of times.",
-    "attribution": "Charles Dickens, A Tale of Two Cities"
+    "category": "business",
+    "content": "Customer obsession, rather than competitor focus, is the surest path to long term success.",
+    "attribution": "Jeff Bezos"
   },
   {
     "category": "movies",
-    "content": "Pixar's first feature film, Toy Story, released in 1995, was the first full length movie created entirely with computer animation.",
+    "content": "The special effects in the original Star Wars trilogy were largely achieved with physical models and practical effects, long before computer generated imagery became common.",
     "attribution": "Film"
   },
   {
-    "category": "business",
-    "content": "Diversification spreads investment risk across different assets, so that a poor outcome in one area does not sink an entire portfolio.",
-    "attribution": "Business"
+    "category": "general",
+    "content": "A group of flamingos is called a flamboyance. The birds get their pink color from the pigments in the shrimp and algae they eat.",
+    "attribution": "General knowledge"
   },
   {
-    "category": "quotes",
-    "content": "It is not the critic who counts; not the man who points out how the strong man stumbles. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood.",
-    "attribution": "Theodore Roosevelt, Citizenship in a Republic"
+    "category": "technology",
+    "content": "Open source software is released with its source code publicly available, allowing anyone to view, modify, and distribute it under the terms of its license.",
+    "attribution": "Technology"
   },
   {
     "category": "programming",
-    "content": "let mut counts: HashMap<String, usize> = HashMap::new();",
+    "content": "match result { Ok(v) => println!(\"{v}\"), Err(e) => eprintln!(\"error: {e}\") }",
     "attribution": "Rust",
-    "language": "rust"
+    "language": "rust",
+    "explanation": "match on a Result must cover both arms - the compiler rejects it otherwise, which is how Rust stops an error going unhandled."
   },
   {
-    "category": "quotes",
-    "content": "The two most important days in your life are the day you are born and the day you find out why.",
-    "attribution": "Mark Twain"
+    "category": "programming",
+    "content": "struct node { int value; struct node *next; };",
+    "attribution": "C",
+    "language": "clike",
+    "explanation": "A linked-list node. It refers to its own type through a pointer, which is legal because a pointer has a known size."
   },
   {
-    "category": "philosophy",
-    "content": "The Socratic method uses a series of questions and answers to expose contradictions in a person's beliefs, encouraging deeper critical thinking rather than simply providing answers.",
-    "attribution": "Philosophy"
+    "category": "programming",
+    "content": "int *buf = malloc(len * sizeof(int)); if (!buf) return -1;",
+    "attribution": "C",
+    "language": "clike",
+    "explanation": "malloc returns NULL when it fails, and checking is not optional. sizeof(int) rather than 4 keeps it correct across platforms."
   },
   {
-    "category": "programming",
-    "content": "const total = items.reduce((acc, item) => acc + item.price, 0);",
-    "attribution": "JavaScript",
-    "language": "javascript"
+    "category": "literature",
+    "content": "It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife. However little known the feelings or views of such a man may be on his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding families.",
+    "attribution": "Jane Austen, Pride and Prejudice"
   },
   {
-    "category": "programming",
-    "content": "counts = {word: text.count(word) for word in set(text.split())}",
-    "attribution": "Python",
-    "language": "python"
+    "category": "science",
+    "content": "Mitochondria convert nutrients into a usable form of energy for the cell, which is why biology textbooks often call them the powerhouse of the cell.",
+    "attribution": "Science"
   },
   {
-    "category": "general",
-    "content": "Honey never spoils if it is stored properly. Archaeologists have found pots of honey in ancient Egyptian tombs that are thousands of years old and still perfectly edible, preserved by its low moisture content and natural acidity.",
-    "attribution": "General knowledge"
+    "category": "nature",
+    "content": "Rivers shape the landscape around them over thousands of years, carving canyons and depositing sediment that forms fertile floodplains.",
+    "attribution": "Nature"
   },
   {
-    "category": "quotes",
-    "content": "Failure is impossible.",
-    "attribution": "Susan B. Anthony"
+    "category": "nature",
+    "content": "The deepest part of the ocean, the Mariana Trench, plunges nearly eleven kilometers below the surface, deeper than Mount Everest is tall.",
+    "attribution": "Nature"
   },
   {
-    "category": "literature",
-    "content": "Mr. Sherlock Holmes, who was usually very late in the mornings, save upon those not infrequent occasions when he was up all night, was seated at the breakfast table.",
-    "attribution": "Arthur Conan Doyle, The Hound of the Baskervilles"
+    "category": "quotes",
+    "content": "If there is no struggle, there is no progress. Those who profess to favor freedom, and yet depreciate agitation, are men who want crops without plowing up the ground.",
+    "attribution": "Frederick Douglass"
   },
   {
     "category": "general",
@@ -510,158 +496,179 @@
     "attribution": "General knowledge"
   },
   {
-    "category": "science",
-    "content": "Evolution by natural selection describes how organisms with traits better suited to their environment tend to survive and reproduce more successfully, gradually shaping a population over many generations.",
-    "attribution": "Science, after Charles Darwin"
+    "category": "programming",
+    "content": "with open('data.csv', encoding='utf-8') as f: rows = [line.split(',') for line in f]",
+    "attribution": "Python",
+    "language": "python",
+    "explanation": "with closes the file even if the body raises. Iterating a file yields lines without loading it all into memory."
   },
   {
-    "category": "quotes",
-    "content": "Success is to be measured not so much by the position that one has reached in life as by the obstacles which he has overcome while trying to succeed.",
-    "attribution": "Booker T. Washington"
+    "category": "nature",
+    "content": "Wolves live and hunt in structured packs, usually led by a breeding pair, and communicate through howls that can be heard for several kilometers.",
+    "attribution": "Nature"
   },
   {
-    "category": "programming",
-    "content": "impl Display for Token { fn fmt(&self, f: &mut Formatter) -> Result { write!(f, \"{}\", self.0) } }",
-    "attribution": "Rust",
-    "language": "rust"
+    "category": "science",
+    "content": "The human body contains roughly thirty seven trillion cells, each one specialized to carry out one of hundreds of different jobs inside the body.",
+    "attribution": "Science"
   },
   {
-    "category": "history",
-    "content": "The invention of the wheel around 3500 BCE is considered one of the most important technological breakthroughs in human history, transforming transportation and trade.",
-    "attribution": "History"
+    "category": "philosophy",
+    "content": "Every new beginning comes from some other beginning's end.",
+    "attribution": "Seneca, Letters from a Stoic"
   },
   {
-    "category": "nature",
-    "content": "The world is big and I want to have a good look at it before it gets dark.",
-    "attribution": "John Muir"
+    "category": "history",
+    "content": "The fall of the Berlin Wall in 1989 marked a turning point in the Cold War, as East and West Germany moved toward reunification the following year.",
+    "attribution": "History"
   },
   {
-    "category": "general",
-    "content": "The first computer programmer is widely considered to be Ada Lovelace, who wrote an algorithm for an early mechanical computer in the eighteen forties, decades before any machine capable of running it was ever built.",
-    "attribution": "General knowledge"
+    "category": "movies",
+    "content": "The word cinema comes from the Greek word for movement, reflecting how early filmmakers were fascinated by the illusion of motion created by a sequence of still images.",
+    "attribution": "Film"
   },
   {
-    "category": "philosophy",
-    "content": "Stoicism is a school of ancient Greek philosophy that teaches the practice of virtue as the only true good, and encourages focusing only on what lies within one's own control.",
-    "attribution": "Philosophy"
+    "category": "nature",
+    "content": "Mycorrhizal fungi form partnerships with the roots of most plants, helping them absorb water and nutrients in exchange for sugars produced by photosynthesis.",
+    "attribution": "Nature"
   },
   {
     "category": "programming",
-    "content": "grep -rn \"TODO\" src/ | awk -F: '{print $1}' | sort -u",
-    "attribution": "Shell",
-    "language": "shell"
+    "content": "counts = {word: text.count(word) for word in set(text.split())}",
+    "attribution": "Python",
+    "language": "python",
+    "explanation": "A dict comprehension. Note it is quadratic: count rescans the whole string per word. collections.Counter is the right tool."
   },
   {
     "category": "general",
-    "content": "Antarctica is technically the largest desert on the planet. Despite being covered in ice, it receives very little precipitation each year, which is the defining characteristic of a desert rather than temperature alone.",
+    "content": "The first computer programmer is widely considered to be Ada Lovelace, who wrote an algorithm for an early mechanical computer in the eighteen forties, decades before any machine capable of running it was ever built.",
     "attribution": "General knowledge"
   },
   {
-    "category": "general",
-    "content": "The shortest war in recorded history was fought between Britain and Zanzibar in 1896. It lasted around forty minutes before Zanzibar surrendered.",
-    "attribution": "General knowledge"
+    "category": "technology",
+    "content": "Robotics combines mechanical engineering, electronics, and computer science to design machines capable of performing tasks autonomously or with minimal human control.",
+    "attribution": "Technology"
   },
   {
-    "category": "nature",
-    "content": "A single mature tree can absorb around twenty two kilograms of carbon dioxide per year, making forests an important part of regulating the planet's climate.",
-    "attribution": "Nature"
+    "category": "literature",
+    "content": "You don't know about me without you have read a book by the name of The Adventures of Tom Sawyer, but that ain't no matter. That book was made by Mr. Mark Twain, and he told the truth, mainly.",
+    "attribution": "Mark Twain, Adventures of Huckleberry Finn"
   },
   {
-    "category": "business",
-    "content": "Cash flow tracks the actual movement of money into and out of a business, which can differ significantly from reported profit due to timing differences in payments.",
-    "attribution": "Business"
+    "category": "movies",
+    "content": "The highest grossing films of all time are dominated by franchises built around superheroes, fantasy worlds, and long running science fiction universes.",
+    "attribution": "Film"
   },
   {
-    "category": "programming",
-    "content": "for (int i = 0; i < n; i++) { sum += a[i] * b[i]; }",
-    "attribution": "C",
-    "language": "clike"
+    "category": "technology",
+    "content": "Cloud computing allows businesses and individuals to rent computing power and storage over the internet instead of maintaining their own physical servers.",
+    "attribution": "Technology"
   },
   {
-    "category": "business",
-    "content": "Price is what you pay, and value is what you get.",
-    "attribution": "Warren Buffett"
+    "category": "technology",
+    "content": "Moore's Law observed that the number of transistors on a computer chip tends to double roughly every two years, driving decades of rapid improvement in computing power.",
+    "attribution": "Technology"
   },
   {
-    "category": "philosophy",
-    "content": "The only true wisdom is in knowing you know nothing.",
-    "attribution": "Socrates"
+    "category": "movies",
+    "content": "Stop motion animation creates the illusion of movement by photographing physical objects one frame at a time and repositioning them slightly between each shot.",
+    "attribution": "Film"
   },
   {
-    "category": "general",
-    "content": "The Eiffel Tower grows about six inches taller in the summer, as the iron structure expands slightly in the heat and contracts again once the weather cools.",
-    "attribution": "General knowledge"
+    "category": "nature",
+    "content": "Heaven is under our feet as well as over our heads.",
+    "attribution": "Henry David Thoreau, Walden"
   },
   {
     "category": "business",
-    "content": "Return on investment measures the profitability of an investment relative to its cost, expressed as a percentage to make it easy to compare different opportunities.",
+    "content": "A merger combines two companies into one, while an acquisition occurs when one company purchases and absorbs another, though the two terms are often used loosely in everyday conversation.",
     "attribution": "Business"
   },
   {
-    "category": "movies",
-    "content": "The Cannes Film Festival, held annually in France since 1946, is considered one of the most prestigious film festivals in the world.",
-    "attribution": "Film"
+    "category": "science",
+    "content": "The periodic table arranges chemical elements by increasing atomic number, grouping elements with similar properties into the same columns.",
+    "attribution": "Science"
   },
   {
-    "category": "history",
-    "content": "The signing of the Magna Carta in 1215 limited the power of the English king and established the principle that even a monarch was subject to the law.",
-    "attribution": "History"
+    "category": "nature",
+    "content": "Deserts are defined by low precipitation rather than temperature, which is why some of the coldest places on Earth, including parts of Antarctica, are technically deserts.",
+    "attribution": "Nature"
+  },
+  {
+    "category": "business",
+    "content": "A monopoly exists when a single company dominates an entire market with no significant competition, often leading regulators to intervene to protect consumers.",
+    "attribution": "Business"
   },
   {
     "category": "movies",
-    "content": "A film's runtime is typically decided during editing, where an editor works with hours of raw footage to shape a coherent story within a manageable length.",
+    "content": "The Wizard of Oz was one of the first major films to use Technicolor extensively, transitioning from black and white to vivid color once Dorothy arrives in Oz.",
     "attribution": "Film"
   },
   {
-    "category": "philosophy",
-    "content": "All men by nature desire to know.",
-    "attribution": "Aristotle, Metaphysics"
+    "category": "science",
+    "content": "Newton's first law of motion states that an object at rest stays at rest, and an object in motion stays in motion, unless acted on by an outside force.",
+    "attribution": "Science"
   },
   {
-    "category": "philosophy",
-    "content": "Waste no more time arguing about what a good man should be. Be one.",
-    "attribution": "Marcus Aurelius, Meditations"
+    "category": "programming",
+    "content": "let total: i64 = values.iter().filter(|v| **v > 0).sum();",
+    "attribution": "Rust",
+    "language": "rust",
+    "explanation": "iter() borrows rather than consuming. The double deref is because filter hands you a reference to the iterator's own reference."
   },
   {
     "category": "technology",
-    "content": "A firewall monitors and controls incoming and outgoing network traffic based on predetermined security rules, acting as a barrier between a trusted network and an untrusted one.",
+    "content": "Machine learning is a branch of artificial intelligence in which a system improves its performance on a task by learning patterns from data rather than following explicit instructions.",
     "attribution": "Technology"
   },
   {
+    "category": "general",
+    "content": "The invention of the printing press in the fifteenth century transformed how knowledge spread across Europe. Books that once took months to copy by hand could suddenly be reproduced by the hundreds, making literacy far more accessible.",
+    "attribution": "General knowledge"
+  },
+  {
     "category": "science",
-    "content": "The theory of plate tectonics explains how the Earth's outer shell is broken into large plates that slowly drift over the mantle, causing earthquakes, volcanoes, and mountain formation.",
+    "content": "DNA carries the genetic instructions for every living organism, encoded in a sequence of four chemical bases that pair together to form the famous double helix shape.",
     "attribution": "Science"
   },
   {
-    "category": "history",
-    "content": "The Great Depression of the 1930s began with the stock market crash of 1929 and led to widespread unemployment and economic hardship across the globe.",
-    "attribution": "History"
+    "category": "business",
+    "content": "A startup's burn rate measures how quickly it spends its available cash, an important number for founders trying to plan how long the company can operate before running out of money.",
+    "attribution": "Business"
   },
   {
-    "category": "movies",
-    "content": "The Wizard of Oz was one of the first major films to use Technicolor extensively, transitioning from black and white to vivid color once Dorothy arrives in Oz.",
-    "attribution": "Film"
+    "category": "philosophy",
+    "content": "Waste no more time arguing about what a good man should be. Be one.",
+    "attribution": "Marcus Aurelius, Meditations"
   },
   {
-    "category": "quotes",
-    "content": "You have power over your mind, not outside events. Realize this, and you will find strength.",
-    "attribution": "Marcus Aurelius, Meditations"
+    "category": "literature",
+    "content": "To Sherlock Holmes she is always the woman. I have seldom heard him mention her under any other name. In his eyes she eclipses and predominates the whole of her sex.",
+    "attribution": "Arthur Conan Doyle, A Scandal in Bohemia"
+  },
+  {
+    "category": "programming",
+    "content": "const total = items.reduce((acc, item) => acc + item.price, 0);",
+    "attribution": "JavaScript",
+    "language": "javascript",
+    "explanation": "reduce walks the array carrying a running value. The 0 is the starting total; drop it and an empty array throws."
   },
   {
     "category": "literature",
-    "content": "The studio was filled with the rich odour of roses, and when the light summer wind stirred amidst the trees of the garden, there came through the open door the heavy scent of the lilac, or the more delicate perfume of the pink-flowering thorn.",
-    "attribution": "Oscar Wilde, The Picture of Dorian Gray"
+    "content": "Buck did not read the newspapers, or he would have known that trouble was brewing, not alone for himself, but for every tide-water dog, strong of muscle and with warm, long hair, from Puget Sound to San Diego.",
+    "attribution": "Jack London, The Call of the Wild"
   },
   {
-    "category": "science",
-    "content": "The periodic table arranges chemical elements by increasing atomic number, grouping elements with similar properties into the same columns.",
-    "attribution": "Science"
+    "category": "general",
+    "content": "A day on Venus is longer than its year. The planet rotates so slowly on its axis that it takes longer to spin around once than it does to complete an entire orbit around the sun.",
+    "attribution": "General knowledge"
   },
   {
     "category": "programming",
-    "content": "for i, v := range items { fmt.Printf(\"%d: %v\\n\", i, v) }",
-    "attribution": "Go",
-    "language": "clike"
+    "content": "try: value = int(raw) except ValueError: value = 0",
+    "attribution": "Python",
+    "language": "python",
+    "explanation": "Catching the specific exception, not a bare except - a bare one would also swallow KeyboardInterrupt."
   },
   {
     "category": "history",
@@ -669,67 +676,112 @@
     "attribution": "Chief Joseph, Nez Perce, 1877"
   },
   {
-    "category": "programming",
-    "content": "try: value = int(raw) except ValueError: value = 0",
-    "attribution": "Python",
-    "language": "python"
+    "category": "nature",
+    "content": "Coral reefs cover less than one percent of the ocean floor, yet they support roughly a quarter of all marine species.",
+    "attribution": "Nature"
+  },
+  {
+    "category": "quotes",
+    "content": "The two most important days in your life are the day you are born and the day you find out why.",
+    "attribution": "Mark Twain"
+  },
+  {
+    "category": "business",
+    "content": "Price is what you pay, and value is what you get.",
+    "attribution": "Warren Buffett"
   },
   {
     "category": "programming",
     "content": "fn main() { println!(\"{}\", args().skip(1).collect::<Vec<_>>().join(\" \")); }",
     "attribution": "Rust",
-    "language": "rust"
+    "language": "rust",
+    "explanation": "skip(1) drops the program name, which is always the first argument. Vec<_> lets the compiler infer the element type."
   },
   {
-    "category": "technology",
-    "content": "Machine learning is a branch of artificial intelligence in which a system improves its performance on a task by learning patterns from data rather than following explicit instructions.",
-    "attribution": "Technology"
+    "category": "literature",
+    "content": "The Time Traveller, for so it will be convenient to speak of him, was expounding a recondite matter to us. His grey eyes shone and twinkled, and his usually pale face was flushed and animated.",
+    "attribution": "H.G. Wells, The Time Machine"
   },
   {
-    "category": "programming",
-    "content": "document.querySelectorAll('.row').forEach(el => el.classList.toggle('active'));",
-    "attribution": "JavaScript",
-    "language": "javascript"
+    "category": "general",
+    "content": "The Eiffel Tower grows about six inches taller in the summer, as the iron structure expands slightly in the heat and contracts again once the weather cools.",
+    "attribution": "General knowledge"
   },
   {
-    "category": "nature",
-    "content": "Heaven is under our feet as well as over our heads.",
-    "attribution": "Henry David Thoreau, Walden"
+    "category": "quotes",
+    "content": "To be great is to be misunderstood.",
+    "attribution": "Ralph Waldo Emerson, Self-Reliance"
   },
   {
-    "category": "business",
-    "content": "A monopoly exists when a single company dominates an entire market with no significant competition, often leading regulators to intervene to protect consumers.",
-    "attribution": "Business"
+    "category": "philosophy",
+    "content": "The only true wisdom is in knowing you know nothing.",
+    "attribution": "Socrates"
+  },
+  {
+    "category": "movies",
+    "content": "The Cannes Film Festival, held annually in France since 1946, is considered one of the most prestigious film festivals in the world.",
+    "attribution": "Film"
+  },
+  {
+    "category": "quotes",
+    "content": "That man over there says that women need to be helped into carriages, and lifted over ditches, and to have the best place everywhere. Nobody ever helps me into carriages, or over mud puddles, or gives me any best place, and ain't I a woman?",
+    "attribution": "Sojourner Truth, Ain't I a Woman?"
+  },
+  {
+    "category": "technology",
+    "content": "A virtual private network encrypts a device's internet connection, helping to protect data from being intercepted while it travels over a public or untrusted network.",
+    "attribution": "Technology"
   },
   {
     "category": "philosophy",
-    "content": "Utilitarianism holds that the right action is the one that produces the greatest good for the greatest number of people, judging morality by outcomes rather than intentions.",
+    "content": "Stoicism is a school of ancient Greek philosophy that teaches the practice of virtue as the only true good, and encourages focusing only on what lies within one's own control.",
     "attribution": "Philosophy"
   },
   {
-    "category": "history",
-    "content": "The Roman Empire at its height stretched from Britain in the north to Egypt in the south, connected by a vast network of roads that still exist in parts of Europe today.",
-    "attribution": "History"
+    "category": "programming",
+    "content": "for f in *.log; do gzip -9 \"$f\" && echo \"packed $f\"; done",
+    "attribution": "Shell",
+    "language": "shell",
+    "explanation": "The quotes around $f matter: without them a filename containing a space becomes two arguments."
   },
   {
-    "category": "literature",
-    "content": "Christmas won't be Christmas without any presents, grumbled Jo, lying on the rug. It's so dreadful to be poor, sighed Meg, looking down at her old dress.",
-    "attribution": "Louisa May Alcott, Little Women"
+    "category": "general",
+    "content": "The shortest war in recorded history was fought between Britain and Zanzibar in 1896. It lasted around forty minutes before Zanzibar surrendered.",
+    "attribution": "General knowledge"
+  },
+  {
+    "category": "business",
+    "content": "The man who dies rich, dies disgraced.",
+    "attribution": "Andrew Carnegie"
+  },
+  {
+    "category": "quotes",
+    "content": "You have power over your mind, not outside events. Realize this, and you will find strength.",
+    "attribution": "Marcus Aurelius, Meditations"
+  },
+  {
+    "category": "programming",
+    "content": "for (int i = 0; i < n; i++) { sum += a[i] * b[i]; }",
+    "attribution": "C",
+    "language": "clike",
+    "explanation": "A dot product. The bound is < n, not <= n; off-by-one here reads past the end of the array."
   },
   {
     "category": "technology",
-    "content": "Artificial intelligence refers to computer systems designed to perform tasks that normally require human intelligence, such as recognizing speech, images, or patterns in data.",
+    "content": "The World Wide Web was invented by Tim Berners-Lee in 1989 as a way to share documents over the internet using hyperlinks.",
     "attribution": "Technology"
   },
   {
     "category": "literature",
-    "content": "Alice was beginning to get very tired of sitting by her sister on the bank, and of having nothing to do. Once or twice she had peeped into the book her sister was reading, but it had no pictures or conversations in it.",
-    "attribution": "Lewis Carroll, Alice's Adventures in Wonderland"
+    "content": "My father's family name being Pirrip, and my Christian name Philip, my infant tongue could make of both names nothing longer or more explicit than Pip. So, I called myself Pip, and came to be called Pip.",
+    "attribution": "Charles Dickens, Great Expectations"
   },
   {
-    "category": "literature",
-    "content": "A throng of bearded men, in sad-colored garments and gray, steeple-crowned hats, intermixed with women, some wearing hoods, and others bareheaded, was assembled in front of a wooden edifice.",
-    "attribution": "Nathaniel Hawthorne, The Scarlet Letter"
+    "category": "programming",
+    "content": "if (typeof value !== 'string' || value.length === 0) { return null; }",
+    "attribution": "JavaScript",
+    "language": "javascript",
+    "explanation": "A guard clause: reject the bad input first and return, instead of nesting the real work inside an if."
   },
   {
     "category": "movies",
@@ -737,140 +789,138 @@
     "attribution": "Film"
   },
   {
-    "category": "technology",
-    "content": "The first practical smartphones combined a mobile phone with computing features such as email, web browsing, and applications, changing how people communicate and work.",
-    "attribution": "Technology"
+    "category": "history",
+    "content": "The Apollo 11 mission landed the first humans on the Moon in July of 1969, when astronauts Neil Armstrong and Buzz Aldrin walked on the lunar surface.",
+    "attribution": "History"
   },
   {
-    "category": "quotes",
-    "content": "To be great is to be misunderstood.",
-    "attribution": "Ralph Waldo Emerson, Self-Reliance"
+    "category": "movies",
+    "content": "Method acting, popularized in the mid twentieth century, encourages performers to draw on personal memories and emotions to portray a character as realistically as possible.",
+    "attribution": "Film"
   },
   {
     "category": "technology",
-    "content": "Robotics combines mechanical engineering, electronics, and computer science to design machines capable of performing tasks autonomously or with minimal human control.",
+    "content": "A blockchain is a distributed ledger that records transactions across many computers, making it difficult to alter any single record without changing every subsequent block.",
     "attribution": "Technology"
   },
   {
-    "category": "movies",
-    "content": "The word cinema comes from the Greek word for movement, reflecting how early filmmakers were fascinated by the illusion of motion created by a sequence of still images.",
-    "attribution": "Film"
-  },
-  {
-    "category": "literature",
-    "content": "Not all those who wander are lost.",
-    "attribution": "J.R.R. Tolkien"
+    "category": "general",
+    "content": "A single bolt of lightning can heat the surrounding air to temperatures hotter than the surface of the sun. The rapid expansion of that superheated air is what produces the crack of thunder we hear moments later.",
+    "attribution": "General knowledge"
   },
   {
-    "category": "nature",
-    "content": "A rainforest canopy can be so dense that less than two percent of sunlight reaches the forest floor below.",
-    "attribution": "Nature"
+    "category": "science",
+    "content": "Genetics research has shown that humans share about ninety-nine percent of their DNA with chimpanzees, the closest living relative to our species.",
+    "attribution": "Science"
   },
   {
     "category": "literature",
-    "content": "Buck did not read the newspapers, or he would have known that trouble was brewing, not alone for himself, but for every tide-water dog, strong of muscle and with warm, long hair, from Puget Sound to San Diego.",
-    "attribution": "Jack London, The Call of the Wild"
+    "content": "The studio was filled with the rich odour of roses, and when the light summer wind stirred amidst the trees of the garden, there came through the open door the heavy scent of the lilac, or the more delicate perfume of the pink-flowering thorn.",
+    "attribution": "Oscar Wilde, The Picture of Dorian Gray"
   },
   {
     "category": "literature",
-    "content": "The Nellie, a cruising yawl, swung to her anchor without a flutter of the sails, and was at rest. The flood had made, the wind was nearly calm, and being bound down the river, the only thing for it was to come to and wait for the turn of the tide.",
-    "attribution": "Joseph Conrad, Heart of Darkness"
+    "content": "In my younger and more vulnerable years my father gave me some advice that I've been turning over in my mind ever since. Whenever you feel like criticizing anyone, he told me, just remember that all the people in this world haven't had the advantages that you've had.",
+    "attribution": "F. Scott Fitzgerald, The Great Gatsby"
   },
   {
-    "category": "general",
-    "content": "Sharks existed long before trees. Fossil evidence suggests that sharks have been swimming in the oceans for more than four hundred million years, while the earliest trees did not appear until tens of millions of years later.",
-    "attribution": "General knowledge"
+    "category": "quotes",
+    "content": "Four score and seven years ago our fathers brought forth on this continent a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.",
+    "attribution": "Abraham Lincoln, The Gettysburg Address"
   },
   {
     "category": "history",
-    "content": "The Renaissance began in Italy in the fourteenth century, sparking a renewed interest in classical art, science, and learning that eventually spread across Europe.",
+    "content": "The Great Depression of the 1930s began with the stock market crash of 1929 and led to widespread unemployment and economic hardship across the globe.",
     "attribution": "History"
   },
   {
-    "category": "philosophy",
-    "content": "The beginning is the most important part of the work.",
-    "attribution": "Plato, The Republic"
+    "category": "literature",
+    "content": "Alice was beginning to get very tired of sitting by her sister on the bank, and of having nothing to do. Once or twice she had peeped into the book her sister was reading, but it had no pictures or conversations in it.",
+    "attribution": "Lewis Carroll, Alice's Adventures in Wonderland"
   },
   {
-    "category": "quotes",
-    "content": "I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived.",
-    "attribution": "Henry David Thoreau, Walden"
+    "category": "philosophy",
+    "content": "Existentialism explores questions about individual freedom, choice, and meaning, arguing that people must create their own purpose in a universe that does not provide one automatically.",
+    "attribution": "Philosophy"
   },
   {
-    "category": "history",
-    "content": "The Silk Road was not a single road but a network of trade routes connecting China to the Mediterranean, carrying silk, spices, and ideas across the ancient world.",
-    "attribution": "History"
+    "category": "science",
+    "content": "Marie Curie remains the only person to win Nobel Prizes in two different sciences, physics and chemistry, for her pioneering research into radioactivity.",
+    "attribution": "Science"
   },
   {
-    "category": "nature",
-    "content": "Migratory birds can travel thousands of miles between breeding and wintering grounds, navigating using the sun, stars, and the Earth's magnetic field.",
-    "attribution": "Nature"
+    "category": "quotes",
+    "content": "If I have seen further, it is by standing on the shoulders of giants.",
+    "attribution": "Isaac Newton"
   },
   {
     "category": "literature",
-    "content": "You don't know about me without you have read a book by the name of The Adventures of Tom Sawyer, but that ain't no matter. That book was made by Mr. Mark Twain, and he told the truth, mainly.",
-    "attribution": "Mark Twain, Adventures of Huckleberry Finn"
-  },
-  {
-    "category": "philosophy",
-    "content": "The impediment to action advances action. What stands in the way becomes the way.",
-    "attribution": "Marcus Aurelius, Meditations"
+    "content": "1801. I have just returned from a visit to my landlord, the solitary neighbour that I shall be troubled with. This is certainly a beautiful country. In all England, I do not believe that I could have fixed on a situation so completely removed from the stir of society.",
+    "attribution": "Emily Bronte, Wuthering Heights"
   },
   {
     "category": "nature",
-    "content": "Rivers shape the landscape around them over thousands of years, carving canyons and depositing sediment that forms fertile floodplains.",
+    "content": "A rainforest canopy can be so dense that less than two percent of sunlight reaches the forest floor below.",
     "attribution": "Nature"
   },
   {
-    "category": "movies",
-    "content": "The first feature length narrative film, The Story of the Kelly Gang, was made in Australia in 1906 and ran for about an hour.",
-    "attribution": "Film"
+    "category": "programming",
+    "content": "def fib(n): return n if n < 2 else fib(n - 1) + fib(n - 2)",
+    "attribution": "Python",
+    "language": "python",
+    "explanation": "Recursion with a base case. Correct but exponential - each call spawns two more, so it recomputes the same values repeatedly."
   },
   {
-    "category": "programming",
-    "content": "const { id, name = 'anonymous', ...rest } = await request.json();",
-    "attribution": "JavaScript",
-    "language": "javascript"
+    "category": "general",
+    "content": "The Amazon rainforest produces roughly twenty percent of the oxygen found in the planet's atmosphere, earning it the nickname the lungs of the Earth.",
+    "attribution": "General knowledge"
   },
   {
-    "category": "science",
-    "content": "DNA carries the genetic instructions for every living organism, encoded in a sequence of four chemical bases that pair together to form the famous double helix shape.",
-    "attribution": "Science"
+    "category": "philosophy",
+    "content": "Utilitarianism holds that the right action is the one that produces the greatest good for the greatest number of people, judging morality by outcomes rather than intentions.",
+    "attribution": "Philosophy"
   },
   {
-    "category": "literature",
-    "content": "The Time Traveller, for so it will be convenient to speak of him, was expounding a recondite matter to us. His grey eyes shone and twinkled, and his usually pale face was flushed and animated.",
-    "attribution": "H.G. Wells, The Time Machine"
+    "category": "business",
+    "content": "The purpose of a business is to create and keep a customer.",
+    "attribution": "Peter Drucker"
   },
   {
-    "category": "quotes",
-    "content": "Stay hungry, stay foolish.",
-    "attribution": "Steve Jobs"
+    "category": "philosophy",
+    "content": "The impediment to action advances action. What stands in the way becomes the way.",
+    "attribution": "Marcus Aurelius, Meditations"
+  },
+  {
+    "category": "programming",
+    "content": "document.querySelectorAll('.row').forEach(el => el.classList.toggle('active'));",
+    "attribution": "JavaScript",
+    "language": "javascript",
+    "explanation": "querySelectorAll returns a static NodeList, so it will not change as you mutate the elements in it."
   },
   {
     "category": "technology",
-    "content": "Moore's Law observed that the number of transistors on a computer chip tends to double roughly every two years, driving decades of rapid improvement in computing power.",
+    "content": "The first practical smartphones combined a mobile phone with computing features such as email, web browsing, and applications, changing how people communicate and work.",
     "attribution": "Technology"
   },
   {
-    "category": "science",
-    "content": "Photosynthesis is the process by which plants convert light energy into chemical energy, using carbon dioxide and water to produce glucose and release oxygen as a byproduct.",
-    "attribution": "Science"
+    "category": "history",
+    "content": "Ancient Egyptian civilization flourished along the Nile River for thousands of years, leaving behind monuments such as the pyramids of Giza and the temples of Luxor.",
+    "attribution": "History"
   },
   {
     "category": "philosophy",
-    "content": "A journey of a thousand miles begins with a single step.",
-    "attribution": "Lao Tzu, Tao Te Ching"
+    "content": "It is not that we have a short time to live, but that we waste a lot of it.",
+    "attribution": "Seneca, On the Shortness of Life"
   },
   {
-    "category": "literature",
-    "content": "1801. I have just returned from a visit to my landlord, the solitary neighbour that I shall be troubled with. This is certainly a beautiful country. In all England, I do not believe that I could have fixed on a situation so completely removed from the stir of society.",
-    "attribution": "Emily Bronte, Wuthering Heights"
+    "category": "business",
+    "content": "Return on investment measures the profitability of an investment relative to its cost, expressed as a percentage to make it easy to compare different opportunities.",
+    "attribution": "Business"
   },
   {
-    "category": "literature",
-    "content": "There was no possibility of taking a walk that day. We had been wandering, indeed, in the leafless shrubbery an hour in the morning, but since dinner the cold winter wind had brought with it clouds so sombre, and a rain so penetrating.",
-    "attribution": "Charlotte Bronte, Jane Eyre"
+    "category": "quotes",
+    "content": "I went to the woods because I wished to live deliberately, to front only the essential facts of life, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived.",
+    "attribution": "Henry David Thoreau, Walden"
   },
   {
     "category": "general",
@@ -878,101 +928,77 @@
     "attribution": "Austin Freeman"
   },
   {
-    "category": "nature",
-    "content": "Mycorrhizal fungi form partnerships with the roots of most plants, helping them absorb water and nutrients in exchange for sugars produced by photosynthesis.",
-    "attribution": "Nature"
-  },
-  {
-    "category": "science",
-    "content": "A black hole forms when a massive star collapses under its own gravity, packing so much mass into so small a space that not even light can escape its pull.",
-    "attribution": "Science"
+    "category": "general",
+    "content": "Honey never spoils if it is stored properly. Archaeologists have found pots of honey in ancient Egyptian tombs that are thousands of years old and still perfectly edible, preserved by its low moisture content and natural acidity.",
+    "attribution": "General knowledge"
   },
   {
-    "category": "quotes",
-    "content": "That man over there says that women need to be helped into carriages, and lifted over ditches, and to have the best place everywhere. Nobody ever helps me into carriages, or over mud puddles, or gives me any best place, and ain't I a woman?",
-    "attribution": "Sojourner Truth, Ain't I a Woman?"
+    "category": "movies",
+    "content": "Silent films relied on live musicians and title cards to convey dialogue and emotion, since synchronized sound was not introduced into feature films until the late 1920s.",
+    "attribution": "Film"
   },
   {
     "category": "general",
-    "content": "The quick brown fox jumps over the lazy dog.",
-    "attribution": "Traditional pangram"
+    "content": "Octopuses have three hearts and blue blood. Two of the hearts pump blood to the gills, while the third circulates it to the rest of the body, and the blue color comes from a copper-based protein instead of iron.",
+    "attribution": "General knowledge"
   },
   {
-    "category": "general",
-    "content": "Venus is the hottest planet in the solar system, even though Mercury sits closer to the sun. A thick blanket of carbon dioxide traps heat at the surface.",
-    "attribution": "General knowledge"
+    "category": "philosophy",
+    "content": "The beginning is the most important part of the work.",
+    "attribution": "Plato, The Republic"
   },
   {
-    "category": "programming",
-    "content": "int *buf = malloc(len * sizeof(int)); if (!buf) return -1;",
-    "attribution": "C",
-    "language": "clike"
+    "category": "business",
+    "content": "Diversification spreads investment risk across different assets, so that a poor outcome in one area does not sink an entire portfolio.",
+    "attribution": "Business"
   },
   {
     "category": "movies",
-    "content": "Citizen Kane, released in 1941, is frequently cited by critics and filmmakers as one of the greatest films ever made, praised for its innovative camera work and narrative structure.",
+    "content": "Pixar's first feature film, Toy Story, released in 1995, was the first full length movie created entirely with computer animation.",
     "attribution": "Film"
   },
   {
-    "category": "literature",
-    "content": "It was on a dreary night of November that I beheld the accomplishment of my toils. With an anxiety that almost amounted to agony, I collected the instruments of life around me, that I might infuse a spark of being into the lifeless thing that lay at my feet.",
-    "attribution": "Mary Shelley, Frankenstein"
-  },
-  {
-    "category": "technology",
-    "content": "Quantum computing uses the principles of quantum mechanics to process information in ways that classical computers cannot, potentially solving certain problems far faster.",
-    "attribution": "Technology"
+    "category": "philosophy",
+    "content": "All men by nature desire to know.",
+    "attribution": "Aristotle, Metaphysics"
   },
   {
     "category": "philosophy",
-    "content": "It does not matter how slowly you go as long as you do not stop.",
-    "attribution": "Confucius, Analects"
+    "content": "The Socratic method uses a series of questions and answers to expose contradictions in a person's beliefs, encouraging deeper critical thinking rather than simply providing answers.",
+    "attribution": "Philosophy"
   },
   {
     "category": "programming",
-    "content": "public static void main(String[] args) { System.out.println(\"ready\"); }",
-    "attribution": "Java",
-    "language": "clike"
+    "content": "grep -rn \"TODO\" src/ | awk -F: '{print $1}' | sort -u",
+    "attribution": "Shell",
+    "language": "shell",
+    "explanation": "grep -n prints file:line:text, awk splits on the colon to take the filename, sort -u removes the duplicates."
   },
   {
-    "category": "quotes",
-    "content": "Our greatest glory is not in never falling, but in rising every time we fall.",
-    "attribution": "Confucius"
+    "category": "literature",
+    "content": "It was on a dreary night of November that I beheld the accomplishment of my toils. With an anxiety that almost amounted to agony, I collected the instruments of life around me, that I might infuse a spark of being into the lifeless thing that lay at my feet.",
+    "attribution": "Mary Shelley, Frankenstein"
+  },
+  {
+    "category": "philosophy",
+    "content": "It does not matter how slowly you go as long as you do not stop.",
+    "attribution": "Confucius, Analects"
   },
   {
     "category": "history",
-    "content": "The Apollo 11 mission landed the first humans on the Moon in July of 1969, when astronauts Neil Armstrong and Buzz Aldrin walked on the lunar surface.",
+    "content": "The Renaissance began in Italy in the fourteenth century, sparking a renewed interest in classical art, science, and learning that eventually spread across Europe.",
     "attribution": "History"
   },
   {
-    "category": "literature",
-    "content": "The year 1866 was signalised by a remarkable incident, a mysterious and inexplicable phenomenon, which doubtless no one has yet forgotten. Ships had met with a huge thing, a long object, spindle-shaped, and at times phosphorescent.",
-    "attribution": "Jules Verne, Twenty Thousand Leagues Under the Sea"
+    "category": "business",
+    "content": "Cash flow tracks the actual movement of money into and out of a business, which can differ significantly from reported profit due to timing differences in payments.",
+    "attribution": "Business"
   },
   {
     "category": "programming",
     "content": "squares = [n * n for n in range(1, 21) if n % 3 != 0]",
     "attribution": "Python",
-    "language": "python"
-  },
-  {
-    "category": "philosophy",
-    "content": "It's not what happens to you, but how you react to it that matters.",
-    "attribution": "Epictetus"
-  },
-  {
-    "category": "nature",
-    "content": "Coral reefs cover less than one percent of the ocean floor, yet they support roughly a quarter of all marine species.",
-    "attribution": "Nature"
-  },
-  {
-    "category": "science",
-    "content": "Newton's first law of motion states that an object at rest stays at rest, and an object in motion stays in motion, unless acted on by an outside force.",
-    "attribution": "Science"
-  },
-  {
-    "category": "technology",
-    "content": "Fiber optic cables transmit data as pulses of light through thin strands of glass, allowing information to travel at extremely high speeds over long distances.",
-    "attribution": "Technology"
+    "language": "python",
+    "explanation": "A list comprehension: the expression, the loop, then the filter. Faster and clearer than appending in a for loop."
   }
 ]
\ No newline at end of file