anchor.diff:  
           map.MapPartition partitioner
   
  -*)
  
positive.code:     /// Removes an element from the domain of the map.
      /// No exception is raised if the element is not present.
      [<CompiledName("Remove")>]
      let inline remove (key : int) (map : HashMap<'Key, 'T>) : HashMap<'Key, 'T> =
          // Preconditions
          checkNonNull "map" map
  
          map.Remove key
  
      /// Returns a new map created by merging the two specified maps.
      [<CompiledName("Union")>]
      let inline union (map1 : HashMap<'Key, 'T>) (map2 : HashMap<'Key, 'T>) : HashMap<'Key, 'T> =
  
negative.code: 
          /// <inherit />
          member __.TryGetValue (key, value) =
              let keyHash = uint32 <| hash key
              match PatriciaHashMap.TryFind (keyHash, key, trie) with
              | None ->
                  false
              | Some v ->
  