code: function sortBy(tree, propertyName) {
      var _this = this;
  
      // It is needed an array structure to sort.
      if (!_.isArray(tree)) tree = [tree];
      tree.forEach(function (item) {
        return _(item).keys().forEach(function (key) {
          if (_.isArray(item[key])) item[key] = _this.sortBy(item[key], propertyName);
        });
      });
      return _.sortBy(tree, propertyName);
    }
docs: Utility function to sort tree by specific property or an array of properties
  @param {array} tree The tree structure to sort
  @param {array|string} propertyName Property names to sort the tree
  @return {array} An array sorted by propertyName