<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def continue_task(cls, logger=None, task_id=_TASK_ID_NOT_SUPPLIED):
 """ Start a new action which is part of a serialized task. @param logger: The L{eliot.ILogger} to which to write messages, or C{None} if the default one should be used. @param task_id: A serialized task identifier, the output of L{Action.serialize_task_id}, either ASCII-encoded bytes or unicode string. Required. @return: The new L{Action} instance. """

        if task_id is _TASK_ID_NOT_SUPPLIED:
            raise RuntimeError("You must supply a task_id keyword argument.")
        if isinstance(task_id, bytes):
            task_id = task_id.decode("ascii")
        uuid, task_level = task_id.split("@")
        action = cls(
            logger, uuid, TaskLevel.fromString(task_level),
            "eliot:remote_task")
        action._start({})
        return action