anchor.diff:  %%      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} ->
  
positive.code: 
  %% @doc Materialize all values in a stream and print to the log.
  %%
  %%      Meant primarily for debugging purposes.
  %%
  get_stream(Head, Output) ->
      lager:info("About to consume: ~p", [Head]),
  
negative.code: %%
  %%      Helper function; used to generate a unique request identifier.
  %%
  mk_reqid() ->
      erlang:phash2(erlang:now()).
  
  