In addition to existing detection of shebang/double hash/doc comments we
consider the following new cases when trying to insert space after '#'
in Python line comments:
* Comments that already start with whitespace are ignored by
formatter.
* Comments that span several lines (up to the first empty line or
non-whitespace element) are not altered either because they may contain
Python code fragments.
* Trailing comments however can be safely adjusted because even if
they contain any code, there cannot be any indentation inside.
Mikhail Golubev