System.Windows.Forms.TreeNode_Old.MoveNext C# (CSharp) Method

        public bool MoveNext()
        {
            if (_current == null) _current = this;
            if (_current.Nodes.Count > 0)
            {
                _current = _current.Nodes[0];
                return true;
            }

            var parentNode = _current.Parent;
            while (parentNode != null && _current._id != this._id)
            {
                if (_current.Index + 1 > parentNode.Nodes.Count)
                {
                    _current = parentNode;
                    parentNode = _current.Parent;
                }
                else
                {
                    _current = parentNode.Nodes[_current.Index];
                    return true;
                }
            }

            return false;
        }
        public void Reset()