pub fn answer(root: &'static Command, args: &[OsString]) -> Option<String>Expand description
Answer a completion script’s callback: args is the command line after
the program’s name. None when it is not a callback, so the program goes
on to parse it.
The callback is __complete_word__ --shell SHELL --line LINE, LINE
being the command line up to the cursor, program name first; bash adds
--bash-word WORD, the part of the current word it will replace (it breaks
words at = and : too). A shell that hands over words already unquoted
(elvish) ends with --words WORD…, the program’s name first, instead of
--line. The answer is one candidate a line, as render writes it.