# File lib/xhtmldiff.rb, line 96
        def change(event)
                begin
                        sd = diff(event.old_element, event.new_element)
                rescue ArgumentError
                        sd = nil
                end
                if sd and (ratio = (Float(rs = sd.to_s.gsub(%r{<(ins|del)>.*</\1>}, '').size) / bs = Math.max(event.old_element.to_s.size, event.new_element.to_s.size))) > 0.5
                        @output << sd
                else
                        @output << wrap(event.old_element, 'del')
                        @output << wrap(event.new_element, 'ins')
                end
  end