public override Yolol.Grammar.AST.Program Visit(Yolol.Grammar.AST.Program program)
            {
                using (AppendLine("```Program:"))
                    base.Visit(program);
                _builder.AppendLine("```");

                return(program);
            }
        public static string PrintAst(this Yolol.Grammar.AST.Program program)
        {
            var b = new StringBuilder();
            var v = new PrintAstVisitor(b);

            v.Visit(program);

            return(b.ToString());
        }