code: function() {
              var categories = { "": 1 };
              for (var i in this.registered_node_types) {
                  if (
                      this.registered_node_types[i].category &&
                      !this.registered_node_types[i].skip_list
                  ) {
                      categories[this.registered_node_types[i].category] = 1;
                  }
              }
              var result = [];
              for (var i in categories) {
                  result.push(i);
              }
              return result;
          }
docs: Returns a list with all the node type categories
  @method getNodeTypesCategories
  @return {Array} array with all the names of the categories