Struggling with names. Removed the print_task which looked at the driver
before printing for uniformity. If I dont do that the printing function
I use to have a safe naming environnment inside tasks are not the same
as the printing function we use for display. So hypothesis displayed dont
actually exists and other bugs.

I will try to see if my changes (in particular clean_environnment and
gen_ident) are necessary.

Modifications in Pretty to get real unique names for hypothesis.