code: func (o *ClientOptions) SetConnectTimeout(t time.Duration) *ClientOptions {
  	o.ConnectTimeout = t
  	return o
  }
docs: // SetConnectTimeout limits how long the client will wait when trying to open a connection
  // to an MQTT server before timeing out and erroring the attempt. A duration of 0 never times out.
  // Default 30 seconds. Currently only operational on TCP/TLS connections.