def get_dir_from_zipfile(zip_file, fallback=None):
    """Return the name of the root folder in a zip file.

    :param zip_file: a :class:`zipfile.ZipFile` instance.
    :param fallback: if `None`, the name of the zip file is used. This is
        returned if the zip file contains more than one top-level directory,
        or none at all.
    """
    fallback = fallback or zip_file.filename
    directories = [name for name in zip_file.namelist() if name.endswith("/")
                   and len(PurePath(name).parts) == 1]
    return fallback if len(directories) > 1 else directories[0]
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