proposition: Lemma length_list_of_string str : List.length (list_of_string str) = String.length str.
proof: Proof. induction str; simpl; rewrite ?IHstr; reflexivity. 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