anchor.diff:  
           if (commands.containsKey(command)) {
             commands[command].add(new CommandEvent(event, command, args));
  +        } else {
  +          commandNotFound(new CommandEvent(event, command, args));
           }
         }
       });
  
positive.code: 
    Map<String, StreamController<CommandEvent>> commands = {
    };
  
    String prefix;
  
  
negative.code:     }
      return true;
    }
  
    void notice(String message, {bool user: true}) => client.notice(user ? from : target, message);
  
    void act(String message) => channel.action(message);
  
    String argument(int index) => args[index];
  }
  