def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
def is_sql_dirty(sql):
    # This should not happen as using bytes in Python 3 is against db protocol,
    # but some people will pass it anyway
    if isinstance(sql, bytes):
        sql = sql.decode()
    # NOTE: not using regex here for speed
    sql = sql.lower()
    for action in ('update', 'insert', 'delete'):
        p = sql.find(action)
        if p == -1:
            continue
        start, end = p - 1, p + len(action)
        if (start < 0 or sql[start] not in CHARS) and (end >= len(sql) or sql[end] not in CHARS):
            return True
    else:
        return False