docs: function (eventNames) {
              
              var events = this._events;
              
              for (var i = 0; i < arguments.length; i++) {
                  var eventName = arguments[i];
                  this._validateName(eventName);
                  
                  if (typeof events[eventName] === 'undefined') {
                      events[eventName] = [];
                  }
              }
              
              return this;
          }