proposition: Lemma uniq_card_tuple : forall (t : n.-tuple T), uniq t -> #|t| = n.
proof: Proof. by move=> t; move/card_uniqP; rewrite size_tuple. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype tuple finset)