anchor.diff:  %%      `riak_dt' behavior.  Type is declared with the provided `Id'.
   %%
   -spec declare(id(), type()) -> {ok, id()} | error().
  -declare(_Id, _Type) ->
  -    {error, not_implemented}.
  +declare(Id, Type) ->
  +    gen_server:call(?MODULE, {declare, Id, Type}, infinity).
   
   %% @doc Update a dataflow variable.
   %%
  
positive.code: %%      variables.
  %%
  -spec fold(id(), function(), id()) -> ok | error().
  fold(_Id, _Function, _AccId) ->
      {error, not_implemented}.
  
  %% @doc Filter values from one lattice into another.
  %%
  
negative.code: %%      provided `Threshold' value.
  %%
  -spec read(id(), threshold()) -> {ok, var()} | error().
  read(Id, Threshold) ->
      gen_server:call(?MODULE, {read, Id, Threshold}, infinity).
  
  %% @doc Blocking monotonic read operation for a list of given dataflow
  %%      variables.
  