code: func (p *pipelineChannel) PushFront(h HandlerTempl) {
  	Handlers := make([]HandlerTempl, len(p.Handlers)+1)
  	Handlers[0] = h
  	copy(Handlers[1:], p.Handlers)
  	p.Handlers = Handlers
  }
docs: // PushFront should not be used after pitaya is running