anchor.diff:  %%
   -spec bind_to(id(), id(), store(), function()) -> {ok, pid()}.
   bind_to(AccId, Id, Store, BindFun) ->
  -    bind_to(AccId, Id, Store, BindFun, ?READ).
  +    bind_to(AccId, Id, Store, BindFun, ?BACKEND_READ).
   
   bind_to(AccId, Id, Store, BindFun, ReadFun) ->
       TransFun = fun({_, _, _, V}) -> V end,
  
positive.code: %%
  -spec fold(id(), function(), id(), store()) -> {ok, pid()}.
  fold(Id, Function, AccId, Store) ->
      fold(Id, Function, AccId, Store, ?BIND, ?READ).
  
  %% @doc Map values from one lattice into another.
  %%
  
negative.code: %%
  -spec map(id(), function(), id(), store()) -> {ok, pid()}.
  map(Id, Function, AccId, Store) ->
      map(Id, Function, AccId, Store, ?BACKEND_WRITE, ?BACKEND_READ).
  
  %% @doc Compute the intersection of two sets.
  %%
  