code: function presentModal(modal) {
      let doc = modal; // assume a document object is passed
      if (_.isString(modal)) { // if a modal document string is passed
          doc = Parser.dom(modal);
      } else if (_.isPlainObject(modal)) { // if a modal page configuration is passed
          doc = Page.makeDom(modal);
      }
      navigationDocument.presentModal(doc);
      modalDoc = doc;
      return doc;
  }
docs: Shows a modal. Closes the previous modal before showing a new modal.
  
  @inner
  @alias module:navigation.presentModal
  
  @param  {Document|String|Object} modal       The TVML string/document representation of the modal window or a configuration object to create modal from
  @return {Document}                           The created modal document