class Kramdown::Converter::Toc

def add_to_toc(el, id)
  toc_element = Element.new(:toc, el, id: id)
  success = false
  until success
    if @stack.empty?
      @toc.children << toc_element
      @stack << toc_element
      success = true
    elsif @stack.last.value.options[:level] < el.options[:level]
      @stack.last.children << toc_element
      @stack << toc_element
      success = true
    else
      @stack.pop
    end
  end
end