private void CreateToolBar()
    {
        Toolbar toolbar = new Toolbar();

        Button nodeCreateButton = new Button(() =>
        {
            // Debug.Log("create button test");
            m_graphView.CreateNormalNode();
        });

        nodeCreateButton.text = "create node";
        toolbar.Add(nodeCreateButton);

        Button branchNodeCreateButton = new Button(() =>
        {
            // Debug.Log("create branch button test");
            m_graphView.CreateBrunchNode();
        });

        branchNodeCreateButton.text = "create branch node";
        toolbar.Add(branchNodeCreateButton);

        TextField nameTextField = new TextField();

        nameTextField.SetValueWithoutNotify(m_graphFileName);
        nameTextField.MarkDirtyRepaint();
        nameTextField.RegisterValueChangedCallback <string>(eventData =>
        {
            m_graphFileName = eventData.newValue;
        });
        toolbar.Add(nameTextField);

        Button saveGraphButton = new Button(() =>
        {
            SaveGraphData();
        });

        saveGraphButton.text = "save data";
        toolbar.Add(saveGraphButton);

        Button loadGraphButton = new Button(() =>
        {
            LoadGraphData();
        });

        loadGraphButton.text = "load data";
        toolbar.Add(loadGraphButton);

        this.rootVisualElement.Add(toolbar);
    }