docs: reflow all markdown files to 80-char width and add control-flow page with branching/looping content

doc/site/lists.markdown

@@ -1,16 +1,21 @@
 ^title Lists
 ^category types
 
-A list is a compound object that holds a collection of elements identified by integer index. You can create a list by placing a sequence of comma-separated expressions inside square brackets:
+A list is a compound object that holds a collection of elements identified by
+integer index. You can create a list by placing a sequence of comma-separated
+expressions inside square brackets:
 
     :::dart
     [1, "banana", true]
 
-Here, we've created a list of three elements. Notice that the elements don't have to be the same type.
+Here, we've created a list of three elements. Notice that the elements don't
+have to be the same type.
 
 ## Accessing elements
 
-You can access an element from a list by calling the [subscript operator](method-calls.html#subscript-operators) on it with the index of the element you want. Like most languages, indexes start at zero:
+You can access an element from a list by calling the [subscript
+operator](expressions.html#subscript-operators) on it with the index of the
+element you want. Like most languages, indexes start at zero:
 
     :::dart
     var hirsute = ["sideburns", "porkchops", "'stache", "goatee"]
@@ -23,34 +28,41 @@ Negative indices counts backwards from the end:
     hirsute[-1] // "goatee".
     hirsute[-2] // "'stache".
 
-It's a runtime error to pass an index outside of the bounds of the list. If you don't know what those bounds are, you can find out using count:
+It's a runtime error to pass an index outside of the bounds of the list. If you
+don't know what those bounds are, you can find out using count:
 
     :::dart
-    hirsute.count // 3.
+    hirsute.count // 4.
 
 ## Slices and ranges
 
-Sometimes you want to slice out a chunk of elements from a list. You can do that by passing a [range](values.html#ranges) to the subscript operator, like so:
+Sometimes you want to copy a chunk of elements from a list. You can do that by
+passing a [range](values.html#ranges) to the subscript operator, like so:
 
     :::dart
     hirsute[1..2] // ["porkchops", "'stache"].
 
-This returns a new list containing the elements of the original list whose indices are within the given range. Both inclusive and exclusive ranges work and do what you expect.
+This returns a new list containing the elements of the original list whose
+indices are within the given range. Both inclusive and exclusive ranges work
+and do what you expect.
 
-Negative bounds also work like they do when passing a single number, so to copy a list, you can just do:
+Negative bounds also work like they do when passing a single number, so to copy
+a list, you can just do:
 
     :::dart
     hirsute[0..-1]
 
 ## Adding elements
 
-Lists are *mutable*, meaning their contents can be changed. You can swap out an existing element in the list using the subscript setter:
+Lists are *mutable*, meaning their contents can be changed. You can swap out an
+existing element in the list using the subscript setter:
 
     :::dart
     hirsute[1] = "muttonchops"
     IO.print(hirsute[1]) // muttonchops.
 
-It's an error to set an element that's out of bounds. To grow a list, you can use `add` to append a single item to the end:
+It's an error to set an element that's out of bounds. To grow a list, you can
+use `add` to append a single item to the end:
 
     :::dart
     hirsute.add("goatee")
@@ -61,9 +73,13 @@ You can insert a new element at a specific position using `insert`:
     :::dart
     hirsute.insert("soul patch", 2)
 
-The first argument is the value to insert, and the second is the index to insert it at. All elements following the inserted one will be pushed down to make room for it.
+The first argument is the value to insert, and the second is the index to
+insert it at. All elements following the inserted one will be pushed down to
+make room for it.
 
-It's valid to "insert" after the last element in the list, but only *right* after it. Like other methods, you can use a negative index to count from the back. Doing so counts back from the size of the list *after* it's grown by one:
+It's valid to "insert" after the last element in the list, but only *right*
+after it. Like other methods, you can use a negative index to count from the
+back. Doing so counts back from the size of the list *after* it's grown by one:
 
     :::dart
     var letters = ["a", "b", "c"]
@@ -74,7 +90,9 @@ It's valid to "insert" after the last element in the list, but only *right* afte
 
 ## Removing elements
 
-The opposite of `insert` is `removeAt`. It removes a single element from a given position in the list. All following items are shifted up to fill in the gap:
+The opposite of `insert` is `removeAt`. It removes a single element from a
+given position in the list. All following items are shifted up to fill in the
+gap:
 
     :::dart
     var letters = ["a", "b", "c"]