code: func NewConn(src, dst net.Conn) *Conn {
  	return &Conn{
  		src:      src,
  		dst:      dst,
  		srcW:     countWriter{w: src},
  		dstW:     countWriter{w: dst},
  		stopping: 0,
  	}
  }
docs: // NewConn returns a conn joining the two given net.Conn