code: function() {
          if (this.parent) {
              var newListItem = document.createElement(CHILD_TAG);
  
              if (this.notesEl) {
                  newListItem.appendChild(this.notesEl);
              }
  
              if (!this.keep) {
                  var el = this.templates.get('removeButton');
                  el.addEventListener('click', this.remove.bind(this));
                  newListItem.appendChild(el);
              }
  
              newListItem.appendChild(this.el);
  
              this.parent.el.querySelector(CHILDREN_TAG).appendChild(newListItem);
          }
      }
docs: Insert each subtree into its parent node along with a "delete" button.
  
  NOTE: The root tree (which has no parent) must be inserted into the DOM by the instantiating code (without a delete button).
  @memberOf FilterNode#