class RDoc::Markup::ToTtOnly

def tt_sections(text)
  flow = @am.flow text.dup
  flow.each do |item|
    case item
    when String then
      @res << item if in_tt?
    when RDoc::Markup::AttrChanger then
      off_tags res, item
      on_tags res, item
    when RDoc::Markup::RegexpHandling then
      @res << convert_regexp_handling(item) if in_tt? # TODO can this happen?
    else
      raise "Unknown flow element: #{item.inspect}"
    end
  end
  res
end