fact: Axiom safe_get_correct : forall s n, String.safe_get s n = Coq.Strings.String.get n (Ocaml.explode s).
imports: Coq.extraction.ExtrOcamlIntConv Coq.ZArith.BinInt Coq.Strings.String Fiat.Common.Coq__8_4__8_5__Compat