anchor.diff:                              counter <- counter + 1
                               keys.[counter] <- keys'.[i]
                               values.[counter] <- values'.[i]
  -                    //if System.Environment.OSVersion.Platform = System.PlatformID.Unix then
  -                    Array.Sort(keys, values, comparer)
  -                    //else
  -                    //    Sort.parallelSort Environment.ProcessorCount keys values
  +                    if box comparer <> null || System.Environment.OSVersion.Platform = System.PlatformID.Unix then
  +                        Array.Sort(keys, values, comparer)
  +                    else
  +                        Sort.parallelSort Environment.ProcessorCount keys values
   
                       values.Take(takeCount).ToArray()
                   return result
  
positive.code:                             counter <- counter + 1
                              keys.[counter] <- projection ctx value
                              values.[counter] <- value
                      //if System.Environment.OSVersion.Platform = System.PlatformID.Unix then
                      Array.Sort(keys, values, comparer)
                      //else
                      //    Sort.parallelSort Environment.ProcessorCount keys values
  
                      new List<_>(Seq.singleton
                                      (keys.Take(takeCount).ToArray(), 
  
negative.code:         let comparer = _PrivateFastGenericComparerTable<'Key>.ValueCanBeNullIfDefaultSemantics
          sortByGen comparer (fun _ctx x -> projection x) takeCount stream 
  
      /// <summary>Applies a key-generating function to each element of the input CloudStream and yields the CloudStream of the given length, ordered using the given comparer for the keys.</summary>
      /// <param name="projection">A function to transform items of the input CloudStream into comparable keys.</param>
      /// <param name="stream">The input CloudStream.</param>
      /// <param name="takeCount">The number of elements to return.</param>
      /// <returns>The result CloudStream.</returns>  
      let inline sortByUsing (projection : 'T -> 'Key) comparer (takeCount : int) (stream : CloudStream<'T>) : CloudStream<'T> = 
          sortByGen comparer (fun _ctx x -> projection x) takeCount stream 
  
      /// <summary>Applies a key-generating function to each element of the input CloudStream and yields the CloudStream of the given length, ordered descending by keys.</summary>
      /// <param name="projection">A function to transform items of the input CloudStream into comparable keys.</param>
      /// <param name="stream">The input CloudStream.</param>
  