}

  // Append a line of code which starts a new block: trailing with '{') and
  // indenting.
  Renderer &BlockOpen(const string &text);
  template <typename... Args>
  Renderer BlockOpen(absl::string_view text, const Args &...args) {
    return BlockOpen(absl::Substitute(text, args...));
  }

  // Append a line of code ending a block: unindenting and adding '}'.

    void Render() {
      CommentLine("File level comment.");
      CodeLine("#include \"header.h\"");
      BlankLine();
      BlockOpen("void TestFunction()");
      {
        Statement("int i = 1");
        BlankLine();
        BlockOpen("while (i == 1)");
        {
          CommentLine("Do nothing, really....");
          CodeLine("#if 0");
          Statement("call()");

}

Renderer& Renderer::CommentLine(const string& text) {
  context_.code.AddLineWithIndent(absl::StrCat("// ", text));
  return *this;
}

Renderer& Renderer::BlockOpen(const string& text) {
  context_.code.AddLineWithIndent(absl::StrCat(text, " {"));
  context_.code.IncreaseIndent();
  return *this;
}

Renderer& Renderer::BlockClose(const string& text) {

    : Renderer(context), op_(op), comment_(context, op) {}

void OpRenderer::Render() {
  comment_.Render();
  if (context_.mode == RendererContext::kHeader) {
    Statement(Signature());
  } else {
    BlockOpen(Signature());
    OpImplementationRenderer(context_, op_).Render();
    BlockClose();
  }
  BlankLine();
}

}  // namespace cpp
}  // namespace generator