anchor.diff:              | 7us -> AnyError
               | _ -> invalidEGT()
   
  -        let readGroup (symbols: ImmutableArray.Builder<_>) fSymbol fGroup index mem =
  +        let readGroup (symbols: ImmutableArray<_>.Builder) fSymbol fGroup index mem =
               lengthMustBeAtLeast mem 7
               let name = wantString mem 0
               let container = wantUInt16 mem 1 |> fSymbol |> wantGroupContainer
  
positive.code:                 GotoActions = GotoActions.ToImmutable()
              }
  
          let itemTry (arr: ImmutableArray.Builder<_>) idx =
              let idx = int idx
              if idx < arr.Count then
                  arr.[idx]
              else
                  invalidEGT()
  
          let readAndAssignIndexed fRead (arr: ImmutableArray.Builder<_>) mem =
              lengthMustBeAtLeast mem 1
              let index = wantUInt16 mem 0
              let content = mem.Slice(1)
  
negative.code:             | AnyGroupEnd of GroupEnd
              | AnyError
  
          let createSafeIndexed<'a> (arr: ImmutableArray<'a>.Builder) idx =
              if int idx <= arr.Capacity then
                  idx |> uint32
              else
  