anchor.diff:      /// <param name="mapper">Mapper function.</param>
       /// <param name="source">Input data.</param>
       let map (mapper : 'T -> Cloud<'S>) (source : seq<'T>) : Cloud<'S []> = 
  -        mapCombine (Sequential.map mapper) (Cloud.lift Array.concat) [||] source
  +        reduceCombine (Sequential.map mapper) (Cloud.lift Array.concat) [||] source
   
       /// <summary>
       ///     Distributed filter combinator. Input data is partitioned according to cluster size
  
positive.code:                 (reducer : 'State -> 'State -> Cloud<'State>)
                  (init : 'State) (source : seq<'T>) : Cloud<'State> =
  
          mapCombine (Sequential.fold folder init) (Sequential.fold reducer init) init source
  
      /// <summary>
      ///     Distributed Map/Reduce workflow with cluster balancing.
  
negative.code:     /// <param name="predicate">Predicate function.</param>
      /// <param name="source">Input data.</param>
      let filter (predicate : 'T -> Cloud<bool>) (source : seq<'T>) : Cloud<'T []> =
          reduceCombine (Sequential.filter predicate) (Cloud.lift Array.concat) [||] source
  
      /// <summary>
      ///     Distributed choose combinator. Input data is partitioned according to cluster size
  