code: func (wf *WriteFlusher) Flushed() bool {
  	// BUG(stevvooe): Remove this method. Its use is inherently racy. Seems to
  	// be used to detect whether or a response code has been issued or not.
  	// Another hook should be used instead.
  	var flushed bool
  	select {
  	case <-wf.flushed:
  		flushed = true
  	default:
  	}
  	return flushed
  }
docs: // Flushed returns the state of flushed.
  // If it's flushed, return true, or else it return false.