public override void EnterExpression_tree(KryptonParser.Expression_treeContext context)
        {
            var parent = _expressionContainers.Peek();
            var group  = new ExpressionTree();

            parent.AddExpresion(group);
            _expressionContainers.Push(group);
        }
 public override void ExitExpression_tree(KryptonParser.Expression_treeContext context)
 {
     _expressionContainers.Pop();
 }