Think about black an white output

[bessarabov]

Now errors are printed in color if you use test_whitespaces. But if you run Test::Whitespaces it in prove it will be printed in black and white.

Maybe in case the color output is not avaliable it is needed to output data with some ascii markes, like

>\t<do();>_<\n;

I'm not sure how to make this output easy to understand.