code: func HijackConnection(w http.ResponseWriter) (io.ReadCloser, io.Writer, error) {
  	conn, _, err := w.(http.Hijacker).Hijack()
  	if err != nil {
  		return nil, nil, err
  	}
  	// Flush the options to make sure the client sets the raw mode
  	conn.Write([]byte{})
  	return conn, conn, nil
  }
docs: // HijackConnection interrupts the http response writer to get the
  // underlying connection and operate with it.