Regex
3.9.2 The Match-end-of-line Operator ($)
This operator can match the empty string either at the end of
the string or before a newline character in the string. Thus, it is
said to anchor the pattern to the end of a line.
It is always represented by `$'. For example, `foo$' usually
matches, e.g., `foo' and, e.g., the first three characters of
`foo\nbar'.
Its interaction with the syntax bits and pattern buffer fields is
exactly the dual of `^''s; see the previous section. (That is,
"beginning" becomes "end", "next" becomes "previous", and
"after" becomes "before".)
