Colorize output in plugin

Hello,
I'm trying to customize a url_handler plugin to colorize terminal output (especially the prompt when connected to a non-colorized host via ssh).
When the callback returns text highlighted (underlined) by escape sequences, it has no effect
> return(r'\033[4mThis is underlined text.\033[0m')

Is there a way to enable escape sequences (similar to `echo -e`) in plugins?

Thanks!
Ondrej