code: function(navListCat, obj) {
          obj = obj || {};
  
          // obj["cat"] is an array; if cat has needed value
          var isSingleTag = !!obj["tag"] && typeof(navListCat) === "string";
          var inArray = isSingleTag
              ? !!~obj["tag"].indexOf(navListCat)
              : !!obj["tag"] && _.reduce(navListCat, function(inArray, item) {
                  return inArray && !!~obj['tag'].indexOf(item);
              }, true);
          // without-cat mode, showing all specs without cat field in info.json defined or
          var isWithoutCat = navListCat === "without-tag" && (!obj["tag"] || obj["tag"].length === 0);
          return !inArray && !isWithoutCat;
      }
docs: @private
  @method skipSpec. Filtering by specified catalogue
  
  @param {String|Array} navListCat catalogue type
  @param {Object} obj - object to filter
  
  @returns {Boolean} true if spec shoud be skipped.