code: function hasCompleteEventParams(eventType, listener) {
          var hasParams = eventType && listener,
              isTypeString = typeof eventType === 'string',
              isTypeFunction = typeof listener === 'function';
  
          if (!isTypeFunction) {
              throw new TypeError(EventDispatcher.TYPE_ERROR);
          }
  
          return hasParams && isTypeString && isTypeFunction;
      }
docs: Checks if params exist and match the correct types.
  @param {String} eventType
  @param {Function} listener
  @returns {Boolean}
  @private
  @throws {TypeError} The listener specified is not a function.