code: function(code, maybeNameOrNames, item) {
              var message = this._options.messages[code],
                  allowedExtensions = [],
                  names = [].concat(maybeNameOrNames),
                  name = names[0],
                  buttonId = this._getButtonId(item),
                  validationBase = this._getValidationBase(buttonId),
                  extensionsForMessage, placeholderMatch;
  
              function r(name, replacement) { message = message.replace(name, replacement); }
  
              qq.each(validationBase.allowedExtensions, function(idx, allowedExtension) {
                  /**
                   * If an argument is not a string, ignore it.  Added when a possible issue with MooTools hijacking the
                   * `allowedExtensions` array was discovered.  See case #735 in the issue tracker for more details.
                   */
                  if (qq.isString(allowedExtension)) {
                      allowedExtensions.push(allowedExtension);
                  }
              });
  
              extensionsForMessage = allowedExtensions.join(", ").toLowerCase();
  
              r("{file}", this._options.formatFileName(name));
              r("{extensions}", extensionsForMessage);
              r("{sizeLimit}", this._formatSize(validationBase.sizeLimit));
              r("{minSizeLimit}", this._formatSize(validationBase.minSizeLimit));
  
              placeholderMatch = message.match(/(\{\w+\})/g);
              if (placeholderMatch !== null) {
                  qq.each(placeholderMatch, function(idx, placeholder) {
                      r(placeholder, names[idx]);
                  });
              }
  
              this._options.callbacks.onError(null, name, message, undefined);
  
              return message;
          }
docs: Constructs and returns a message that describes an item/file error.  Also calls `onError` callback.
  
  @param code REQUIRED - a code that corresponds to a stock message describing this type of error
  @param maybeNameOrNames names of the items that have failed, if applicable
  @param item `File`, `Blob`, or `<input type="file">`
  @private