code: func (crw *customResponseWriter) Write(body []byte) (int, error) {
  	if crw.written {
  		LOGHANDLER.Warn(errMultiWrite)
  		return 0, nil
  	}
  
  	crw.written = true
  	return crw.ResponseWriter.Write(body)
  }
docs: // Write is the interface implementation to respond to the HTTP request,
  // but check if a response was already sent.