# File lib/heckle.rb, line 705
    def diff(original, mutation)
      length = [original.split(/\n/).size, mutation.split(/\n/).size].max

      Tempfile.open("orig") do |a|
        a.puts(original)
        a.flush

        Tempfile.open("fail") do |b|
          b.puts(mutation)
          b.flush

          diff_flags = " "

          output = `#{Heckle::DIFF} -U #{length} --label original #{a.path} --label mutation #{b.path}`
          puts output.sub(/^@@.*?\n/, '')
          puts
        end
      end
    end