code: func (p *Processor) SetRawHandler(msgID string, msgRawHandler MsgHandler) {
  	i, ok := p.msgInfo[msgID]
  	if !ok {
  		log.Fatal("message %v not registered", msgID)
  	}
  
  	i.msgRawHandler = msgRawHandler
  }
docs: // It's dangerous to call the method on routing or marshaling (unmarshaling)