Returns `True` if the given `possible_identifier` can be used as an
    identifier in Python 2.

def is_python2_identifier(possible_identifier):
    """
    Returns `True` if the given `possible_identifier` can be used as an
    identifier in Python 2.
    """
    match = _python2_identifier_re.match(possible_identifier)
    return bool(match) and not iskeyword(possible_identifier)