code: function(themeName, extOptions) {
          var options = presetOptions[themeName];
  
          if (!options) {
              options = presetOptions[themeNameConst.DEFAULT];
          }
          options = $.extend(true, {}, options, extOptions);
          setDocumentStyle(options);
      }
docs: Creates a style element using theme options identified by given name,
  and appends it to the document.
  @param {String} themeName - preset theme name
  @param {Object} extOptions - if exist, extend preset theme options with it.