# File lib/rdoc/parser.rb, line 199
  def self.use_markup content
    markup = content.lines.first(3).grep(/markup:\s+(\w+)/) { $1 }.first

    return unless markup

    return RDoc::Parser::Ruby if markup == 'tomdoc'

    markup = Regexp.escape markup

    RDoc::Parser.parsers.find do |_, parser|
      /^#{markup}$/i =~ parser.name.sub(/.*:/, '')
    end.last
  end