// traverse
			_get_node		: function (obj) {
				var $obj = $(obj, this.get_container());
				if($obj.is(".jstree") || obj == -1) { return -1; }
				$obj = $obj.closest("li", this.get_container());
				return $obj.length ? $obj : false;
			},
			_get_next		: function (obj, strict) {
				obj = this._get_node(obj);
				if(obj === -1) { return this.get_container().find("> ul > li:first-child"); }
				if(!obj.length) { return false; }

    abstract boolean isSupportsBuildOperations()

    abstract DomainObjectCollection<T> getContainer()

    abstract T getA()

    abstract T getB()

    abstract T getC()

    abstract <S extends T> S getD()

    Class<T> getType() {
        return a.class
    }