eaming deserialize from socket::

        unpacker = Unpacker()
        while True:
            buf = sock.recv(1024**2)
            if not buf:
                break
            unpacker.feed(buf)
            for o in unpacker:
                process(o)

    Raises ``ExtraData`` when *packed* contains extra bytes.
    Raises ``OutOfData`` when *packed* is incomplete.
    Raises ``FormatError`` when *packed* is not valid msgpack.
    Raises ``StackError`` when *packed* contains too nested.
    Other exceptions can be raised during unpacking.
    Nr