text: 
  import { NativeModules, DeviceEventEmitter } from 'react-native';
  
  const { RNWebsocketServer } = NativeModules;
  
  const callback_default = () => { console.warn('are you sure not contain callback ?') }
  
  
  export default class WebsocketServer {  
    constructor (ipAddress = '127.0.0.0', port = 50005, callback = callback_default) {
      this.ipAddress  = ipAddress;
      this.port       = port;
      this.callback   = callback;
    }
  
    start () {
      RNWebsocketServer.start(this.ipAddress, this.port);
      DeviceEventEmitter.addListener('RNWebsocketServerResponeReceived', this.callback);
    }
  
    stop () {
      RNWebsocketServer.stop();
      DeviceEventEmitter.removeListener('RNWebsocketServerResponeReceived');
    }
  
    send(requestId, body) {
      RNWebsocketServer.send(requestId, body);
    }
  }