Maybe you could just define [here](https://github.com/vmg/redcarpet/blob/7b48ac95d9b3a140549aebdb209c6ee64eb6efdf/test/html_render_test.rb#L5-L15) an `:with_toc_data` entry so we could use a render with this option enabled elsewhere. Also, we could rely on the `@markdown` variable instead of creating a new parser. What do you think?