anchor.diff:  let ``tryHead returns Some head when the heap is not empty`` () =
       fsCheck <| fun { Heap = heap; Items = orig } -> 
           heap |> SkewBinomialHeap.isEmpty |> not ==> 
  -            lazy(
  -                match SkewBinomialHeap.tryHead heap with 
  -                | Some head -> head |> should equal <| actualHead heap orig
  -                | None -> fail "tryHead to a non-empty heap returned None")
  +        match SkewBinomialHeap.tryHead heap with 
  +        | Some head -> head = actualHead heap orig
  +        | None -> false
   
   [<Test>]
   let ``tryHead returns None when the heap is empty`` () =
       fsCheck <| fun { Heap = heap } ->
  -        heap |> SkewBinomialHeap.isEmpty ==> lazy (heap |> SkewBinomialHeap.tryHead |> Option.isNone)
  +        heap |> SkewBinomialHeap.isEmpty ==> (heap |> SkewBinomialHeap.tryHead |> Option.isNone)
   
   [<Test>]
   let ``tail returns a heap with the first element removed when the heap is not empty`` () =
       fsCheck <| fun { Heap = heap; Items = orig } ->
  -        heap |> SkewBinomialHeap.isEmpty |> not ==> lazy(heap |> SkewBinomialHeap.tail |> SkewBinomialHeap.toList |> should equal <| actualTail heap orig)
  +        heap |> SkewBinomialHeap.isEmpty |> not ==> lazy(heap |> SkewBinomialHeap.tail |> SkewBinomialHeap.toList = actualTail heap orig)
   
   [<Test>]
   let ``tail throws when the heap is empty`` () =
  
positive.code:             lazy(
                  match SkewBinomialHeap.tryUncons heap with 
                  | Some (h, t) ->
                      h |> should equal (actualHead heap orig)
                      t |> SkewBinomialHeap.toList |> should equal (actualTail heap orig)
                  | None -> fail "tryUncons to a non-empty heap returned None")
  
  [<Test>]
  let ``tryUncons returns None when the heap is empty`` () =
  
negative.code: 
  [<Test>]
  let ``merge should merge if both heaps have the same ordering`` () =
      fsCheck <| fun ({ Heap = heap1; Items = orig1 }, { Heap = heap2; Items = orig2 }) ->
          heap1.IsDescending = heap2.IsDescending ==>
          lazy(
              SkewBinomialHeap.merge heap1 heap2 
  