Implement take command and comments (--) + misc cleanup

HELP.md

@@ -62,6 +62,18 @@ str %> replace oo OO; replace ba BA
 str %>
 ```
 
+Comments start with `--` and run through the end of the line. Example:
+
+```text
+str %> = abc  -- my comment
+┌───────────────
+│ 0 │abc
+├───────────────
+│ :: string
+└───────────────
+str %>
+```
+
 
 ## Data Types
 
@@ -231,6 +243,12 @@ Delete the specified word/line/index from the current subject.
 `index` is applied for destructured subjects. For destructured subjects you may omit the type (e.g. `drop 4`).
 Example: `foo bar baz` -> `drop word 1` -> `foo baz`
 
+#### `take <word|line|index> <index>`
+Keep only the specified word/line/index from the current subject.
+`word` and `line` apply to strings that have not been destructured.
+`index` is applied for destructured subjects. For destructured subjects you may omit the type (e.g. `take 4`).
+Example: `foo bar baz` -> `take word 1` -> `bar`
+
 #### `contains <find>`
 If the subject contains the given substring, keep it. Otherwise, replace it with an empty string.
 Most often used in conjunction with `line`, `word`, or `each` for filtering.