# File lib/rdoc/markup/attribute_manager.rb, line 96
  def changed_attribute_by_name current_set, new_set
    current = new = 0
    current_set.each do |name|
      current |= RDoc::Markup::Attribute.bitmap_for(name)
    end

    new_set.each do |name|
      new |= RDoc::Markup::Attribute.bitmap_for(name)
    end

    change_attribute(current, new)
  end