code: func ObfsHTTPListener(addr string) (Listener, error) {
  	laddr, err := net.ResolveTCPAddr("tcp", addr)
  	if err != nil {
  		return nil, err
  	}
  	ln, err := net.ListenTCP("tcp", laddr)
  	if err != nil {
  		return nil, err
  	}
  	return &obfsHTTPListener{Listener: tcpKeepAliveListener{ln}}, nil
  }
docs: // ObfsHTTPListener creates a Listener for HTTP obfuscating tunnel server.