class Kramdown::Converter::Base

def in_toc?(el)

specified by the +toc_levels+ option).
Return +true+ if the header element +el+ should be used for the table of contents (as 
def in_toc?(el)
  @options[:toc_levels].include?(el.options[:level]) and ((not el.attr['class'].split.include?('no_toc')) rescue true)
end