anchor.diff:  
               match result with
               | None -> return! Cloud.Raise (new System.ArgumentException("The input flow was empty.", "flow"))
  -            | Some (maxVal, _) -> return maxVal
  +            | Some (maxVal, _) -> return !maxVal
           }
   
       /// <summary>Locates the minimum element of the flow by given key.</summary>
  
positive.code:         cloud {
              let! result =
                  foldGen (fun _ state x ->
                               let keyOfX = projection x
                               match state with
                               | None -> Some (x, keyOfX)
                               | Some (value, keyOfValue) when keyOfValue > keyOfX -> Some (x, keyOfX)
                               | _ -> state)
                          (fun _ left right ->
                               match left, right with
                               | Some (_, leftKey), Some (_, rightKey) -> if rightKey > leftKey then left else right
                               | None, _ -> right
                               | _, None -> left)
                          (fun _ -> None)
  
negative.code:         cloud {
              let! result =
                  foldGen (fun _ state x ->
                                 let kx = projection x
                                 match state with
                                 | None -> Some (ref x, ref kx)
                                 | Some (v, k) when !k < kx ->
                                     v := x
                                     k := kx
                                     state
                                 | _ -> state)
                          (fun _ left right ->
                               match left, right with
                               | Some (_, k), Some (_, k') -> if !k' > !k then right else left
                               | None, _ -> right
                               | _, None -> left)
                          (fun _ -> None)
  