in pyqldb/util/qldb_hash.py [0:0]
def __init__(self, qldb_hash):
if qldb_hash is None or (len(qldb_hash) != HASH_SIZE and len(qldb_hash) != 0):
raise ValueError('Hash must either be empty or {} bytes long'.format(HASH_SIZE))
self._qldb_hash = qldb_hash