public void Visit(Block block)
        {
            _sb.Append(" {");
            ++Level;
            foreach (var stmt in block.Statements)
            {
                _sb.Append("\n");
                Indent();
                stmt.Accept(this);

            }
            _sb.Append("\n");
            --Level;
            Indent();
            _sb.Append("}");
        }
 public void Visit(Block block)
 {
     foreach (var s in block.Statements)
     {
         s.Accept(this);
     }
 }