public SimpleNode CreateBrunchNode(System.Guid guid = default)
    {
        if (default == guid)
        {
            guid = System.Guid.NewGuid();
        }

        SimpleNode node = SimpleNodeUtil.CreateNode(SimpleNodeType.BranchNode, guid);

        node.title = $"branch node - {node.m_guidShortStr}";
        node.SetPosition(new Rect(400.0f, 400.0f, NODE_SIZE.x, NODE_SIZE.y));
        AddElement(node);
        return(node);
    }
    public SimpleNode CreateStartNode(System.Guid guid = default)
    {
        if (default == guid)
        {
            guid = System.Guid.NewGuid();
        }

        SimpleNode node = SimpleNodeUtil.CreateNode(SimpleNodeType.StartNode, guid);

        node.title = $"start node - {node.m_guidShortStr}";
        node.SetPosition(new Rect(400.0f, 400.0f, 200.0f, 200.0f));
        AddElement(node);
        return(node);
    }