fact: Definition first_char_in__impl__for_first_char {str ls} {P : _ -> Prop} (H : forall ch, List.In ch ls -> P ch) : impl (first_char_in str ls) (for_first_char str P).
imports: Fiat.Common.Coq__8_4__8_5__Compat Coq.ZArith.ZArith Fiat.Parsers.StringLike.Core Fiat.Parsers.StringLike.Properties Fiat.Parsers.StringLike.ForallChars Fiat.Common