code: func (engine *Engine) Run(addr ...string) (err error) {
  	defer func() { debugPrintError(err) }()
  
  	address := resolveAddress(addr)
  	debugPrint("Listening and serving HTTP on %s\n", address)
  	err = http.ListenAndServe(address, engine)
  	return
  }
docs: // Run attaches the router to a http.Server and starts listening and serving HTTP requests.
  // It is a shortcut for http.ListenAndServe(addr, router)
  // Note: this method will block the calling goroutine indefinitely unless an error happens.