fact: Definition GetByteAt {n : nat} (idx : nat) : AlignedDecodeM char n := fun v idx' c => Ifopt (nth_opt v idx) as b Then Some (b, idx', c) Else None.
imports: Fiat.Common.Coq__8_4__8_5__Compat Bedrock.Word Coq.ZArith.ZArith Coq.NArith.NArith Coq.Arith.Arith Coq.Numbers.Natural.Peano.NPeano Coq.Logic.Eqdep_dec Fiat.Narcissus.Common.Specs Fiat.Narcissus.BinLib.Core Fiat.Narcissus.BinLib.AlignedByteString