fact: Definition tuto_prod_enum (T1 T2 : finType) : seq (T1 * T2) := foldr (fun x1 => cat (map (pair x1) (enum T2))) [::] (enum T1).
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype tuple finset)