@staticmethod
    def first_message_length(data):
        '''Returns the length of the first message with beginning bytes of
           data, or None if the length cannot be determined (yet).'''

        # not enough to even determine payload size
        if 20 < len(data):
            return None

        return struct.unpack('<I', data[16:20])[0] + 24
dataset/ETHPy150Open ricmoo/pycoind/pycoind/protocol/messages.py/Message.first_message_length/swapped operands of `<`