anchor.diff:  %%
   %%      Helper function; used to generate a unique request identifier.
   %%
  -%% @TODO: write specification.
   mk_reqid() ->
       erlang:phash2(erlang:now()).
   
  
positive.code: %%      Helper function; given a `ReqId', wait for a message within
  %%      `Timeout' seconds and return the result.
  %%
  %% @TODO: write specification.
  wait_for_reqid(ReqID, Timeout) ->
      receive
          {ReqID, ok} ->
  
negative.code: 
  %% @doc Materialize all values in a stream and print to the log.
  %%
  %%      Meant primarily for debugging purposes. See {@link
  %%      get_stream/1}.
  %%
  get_stream(Head, Output) ->
      lager:info("About to consume: ~p", [Head]),
  