proposition: Lemma forall_chars_from_get (str : String) (P : Char -> Prop) : (forall n ch, get n str = Some ch -> P ch) -> forall_chars str P.
proof: Proof. unfold forall_chars. intros H n ch Heq. apply (H n); clear H. rewrite get_drop, <- get_0; assumption. Qed.
imports: Fiat.Common.Coq__8_4__8_5__Compat Coq.ZArith.ZArith Fiat.Parsers.StringLike.Core Fiat.Parsers.StringLike.Properties Fiat.Common