'_match_long_opt(opt : string) -> string
Determine which long option string \'opt\' matches, ie. which one
it is an unambiguous abbrevation for.  Raises BadOptionError if
\'opt\' doesn\'t unambiguously match any long option string.'

def _match_long_opt(self, opt):

    return _match_abbrev(opt, self._long_opt)
