anchor.diff:   */
   
   class MqttSubOptions {
  -  static Map<String, String> optionList = {
  -                        '-?': 'display help message',
  -                        '-c': 'disable clean session',
  -                        '-d': 'enable debug message',
  -                        '-h': 'host to connect to. Default is 127.0.0.1',
  -                        '-p': 'port to connect to. Default is 1883',
  -                        '-i': 'client ID',
  -                        '-k': 'keep alive in seconds. Defaults is 60',
  -                        '-t': 'topic',
  -                        '-m': 'message payload',
  -                        '-q': 'quality of service. Default is 0',
  -                        '-u': 'provide a username',
  -                        '-P': 'provide a password',
  -                        '--will-payload': 'payload for the client will',
  -                        '--will-qos': 'quality of service for the client will',
  -                        '--will-retain': 'if provided, make the client will retain',
  -                        '--will-topic': 'the topic on which to publish the client will'};
     
     bool debugMessage = false;
     bool cleanSession = true;
  
positive.code: }
  void onConnectionLost() {
    print("Connection lost");
  }
negative.code: import 'dart:io';
  import 'package:mqtt/mqtt_shared.dart';
  import 'package:mqtt/mqtt_connection_io_socket.dart';
  import 'package:args/args.dart';
  
  /**
   * mqtt_sub
  