def _match_abbrev(s, wordmap):
    """_match_abbrev(s : string, wordmap : {string : Option}) -> string

    Return the string key in 'wordmap' for which 's' is an unambiguous
    abbreviation.  If 's' is found to be ambiguous or doesn't match any of
    'words', raise BadOptionError.
    """
    # Is there an exact match?
    if s in wordmap:
        return s
    else:
        # Isolate all words with s as a prefix.
        possibilities = [word for word in wordmap.keys()
                         if word.startswith(s)]
        # No exact match, so there had better be just one possibility.
        if len(possibilities) == 1:
            return possibilities[0]
        elif not possibilities:
            raise BadOptionError(s)
        else:
            # More than one possible completion: ambiguous prefix.
            possibilities.sort()
            raise AmbiguousOptionError(s, possibilities)


# Some day, there might be many Option classes.  As of Optik 1.3, the
# preferred way to instantiate Options is indirectly, via make_option(),
# which will become a factory function when there are many Option
# classes.
dataset/ETHPy150Open azoft-dev-team/imagrium/env/Lib/optparse.py/_match_abbrev/original