struct IndentedToStringVisitor : flatbuffers::ToStringVisitor {
  std::string indent_str;
  int indent_level;

  IndentedToStringVisitor(const std::string& delimiter,
                          const std::string& indent)
      : ToStringVisitor(delimiter), indent_str(indent), indent_level(0) {}

  void indent() {
    for (int i = 0; i < indent_level; ++i) s.append(indent_str);
  }

  // Adjust indention for fields in sequences.