anchor.diff:      let s = run (fun () -> xs |> Seq.find predicate)
       let l = run (fun () -> xs |> List.ofArray |> List.find predicate)
       let a = run (fun () -> xs |> Array.find predicate)
  -    consistency "filter" s l a
  +    consistency "find" s l a
   
   [<Test>]
   let ``find is consistent`` () =
  
positive.code:             if !c > 100 then None else // prevent infinity seqs
              c := !c + 1
              f x
  
      
      let s : 'b [] = Seq.unfold (f()) start |> Seq.toArray
      let l = List.unfold (f()) start |> List.toArray
      let a = Array.unfold (f()) start
  
negative.code: let append<'a when 'a : equality> (xs : list<'a>) (xs2 : list<'a>) =
      let s = xs |> Seq.append xs2 |> Seq.toArray
      let l = xs |> List.append xs2 |> List.toArray
      let a = xs |> List.toArray |> Array.append (List.toArray xs2)
      consistency "append" s l a
  
  
  