anchor.diff:           findKey/2,
            fold/3,
            % foldBack/3,
  -         % forall/2,
  +         forall/2,
            isEmpty/1,
            % iter/2,
            map/2,
            % ofArray/1,
  -         % ofList/1,
  -         % ofSeq/1,
  +         ofList/1,
  +         ofSeq/1,
            % partition/3,
            % pick/2,
            remove/2,
            % toArray/1,
            toList/1,
  -         % toSeq/1,
  -         tryFind/2
  -         % tryFindKey/3,
  -         % tryPick/2
  +         toSeq/1,
  +         tryFind/2,
  +         tryFindKey/2,
  +         tryPick/2
           ]).
   
  +-define(SEQ_MOD, 'Microsoft.FSharp.Collections.SeqModule').
   
   add(K, V, M) ->
       maps:put(K, V, M).
  
positive.code:                       F(Acc, K, V)
                end, S, M).
  
  isEmpty(#{}) -> true;
  isEmpty(_) -> false.
  
  
negative.code:                   (K, V, false) ->
                        P(K, V)
                end, false, M).
  
  ofList(List) ->
      maps:from_list(List).
  
  ofSeq(Seq) ->
      maps:from_list(?SEQ_MOD:toList(Seq)).
  
  filter(P, M) ->
      maps:filter(P, M).
  