def METHOD_NAME(self):
    """
    serialization_id is used to keep items locally sorted and unique
    eg:
    activity.serialization_id = 1373266755000000000042008
    1373266755000 activity creation time as epoch with millisecond resolution
    0000000000042 activity left padded object_id (10 digits)
    008 left padded activity verb id (3 digits)
    """
    if not self.object_id:
        raise TypeError("Cant serialize activities without a object")
    if self.object_id >= 10**10 or self.verb.id >= 10**3:
        raise TypeError("Fatal: object_id / verb have too many digits!")
    if not self.time:
        raise TypeError("Cant serialize activities without a time")
    milliseconds = str(int(self.time.timestamp() * 1000))
    serialization_id_str = "%s%0.10d%0.3d" % (
        milliseconds,
        self.object_id,
        self.verb.id,
    )
    serialization_id = int(serialization_id_str)
    return serialization_id