code: func (msm *MultistreamMuxer) Handle(rwc io.ReadWriteCloser) error {
  	p, h, err := msm.Negotiate(rwc)
  	if err != nil {
  		return err
  	}
  	return h(p, rwc)
  }
docs: // Handle performs protocol negotiation on a ReadWriteCloser
  // (i.e. a connection). It will find a matching handler for the
  // incoming protocol and pass the ReadWriteCloser to it.