code: def onMessageSeen(
          self,
          seen_by=None,
          thread_id=None,
          thread_type=ThreadType.USER,
          seen_ts=None,
          ts=None,
          metadata=None,
          msg=None,
      ):
          
          log.info(
              "Messages seen by {} in {} ({}) at {}s".format(
                  seen_by, thread_id, thread_type.name, seen_ts / 1000
              )
          )
docs: Called when the client is listening, and somebody marks a message as seen
  
          :param seen_by: The ID of the person who marked the message as seen
          :param thread_id: Thread ID that the action was sent to. See :ref:`intro_threads`
          :param thread_type: Type of thread that the action was sent to. See :ref:`intro_threads`
          :param seen_ts: A timestamp of when the person saw the message
          :param ts: A timestamp of the action
          :param metadata: Extra metadata about the action
          :param msg: A full set of the data recieved
          :type thread_type: models.ThreadType