proposition: Lemma string_concat_empty_r {s} : (s ++ "" = s)%string.
proof: Proof. induction s; simpl; f_equal; trivial. Qed.
imports: Fiat.Common.Coq__8_4__8_5__Compat Coq.ZArith.ZArith Coq.Arith.PeanoNat Coq.Strings.Ascii Coq.Strings.String Fiat.Common.List.Operations Fiat.Common.StringOperations