# File lib/rdoc/markup/attribute_manager.rb, line 178
  def mask_protected_sequences
    # protect __send__, __FILE__, etc.
    @str.gsub!(/__([a-z]+)__/i,
      "_#{PROTECT_ATTR}_#{PROTECT_ATTR}\\1_#{PROTECT_ATTR}_#{PROTECT_ATTR}")
    @str.gsub!(/\\([#{Regexp.escape @protectable.join('')}])/,
               "\\1#{PROTECT_ATTR}")
  end