anchor.diff:      let s = runAndCheckErrorType (fun () -> Seq.forall2 f xs xs2)
       let l = runAndCheckErrorType (fun () -> List.forall2 f (List.ofSeq xs) (List.ofSeq xs2))
       let a = runAndCheckErrorType (fun () -> Array.forall2 f (Array.ofSeq xs) (Array.ofSeq xs2))
  -    s = a && l = a
  +    consistency "forall2" s l a
       
   [<Test>]
   let ``forall2 is consistent for collections with equal length`` () =
  
positive.code:     let s = run (fun () -> xs |> Seq.fold f start)
      let l = run (fun () -> xs |> List.ofArray |> List.fold f start)
      let a = run (fun () -> xs |> Array.fold f start)
      s = a && l = a
  
  [<Test>]
  let ``fold is consistent`` () =
  
negative.code:     let s = run (fun () -> xs |> Seq.scan f start |> Seq.toArray)
      let l = run (fun () -> xs |> List.ofArray |> List.scan f start |> Seq.toArray)
      let a = run (fun () -> xs |> Array.scan f start)
      consistency "scan" s l a
  
  [<Test>]
  let ``scan is consistent`` () =
  