proposition: Lemma eqEtuple (t1 t2 : n.-tuple T) : (t1 == t2) = [forall i, tnth t1 i == tnth t2 i].
proof: Proof. by apply/eqP/'forall_eqP => [->|/eq_from_tnth]. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq choice fintype path)