collapseAll() {
    this.#nodes.filter((n) => n.elem.isGroup).forEach((n) => {
      n.elem.expanded = false;
    });
  }
/**
   * Collapse all attached nodes to the tree
   * @returns {void}
   */
Collapse all attached nodes to the tree
@returns {void}
Collapse all attached nodes to the tree @returns { void }
collapseAll() {
    this.#nodes.filter((n) => n.elem.isGroup).forEach((n) => {
      n.elem.expanded = false;
    });
  }
collapseAll ( ) { this . #nodes . filter ( ( n ) => n . elem . isGroup ) . forEach ( ( n ) => { n . elem . expanded = false ; } ) ; }
Collapse all attached nodes to the tree
 @returns {void}
Collapse all attached nodes to the tree @returns { void }