code: function (name, version) {
      if (!name || !_.isString(name)) {
        var err = new Error('Please pass a valid string as name!');
        debug(err);
        throw err;
      }
  
      version = version || 0;
  
      if (!_.isNumber(version)) {
        var err = new Error('Please pass a valid number as version!');
        debug(err);
        throw err;
      }
  
      var handler =  _.find(this.commandHandlers, function (cmdHnd) {
        return cmdHnd.name === name && cmdHnd.version === version;
      });
  
      if (handler) {
        return handler;
      }
  
      if (!this.getCommand(name, version)) {
        return null;
      }
  
      return this.defaultCommandHandler;
    }
docs: Returns the commandHandler module by command name and command version.
  @param {String} name    The command name.
  @param {Number} version The command version. [optional; default 0]
  @returns {CommandHandler}