code: <TInput, TOutput> void sendAggregateFunction(final int aggregateFunctionId,
                                                 final VortexAggregateFunction<TOutput> aggregateFunction,
                                                 final VortexFunction<TInput, TOutput> function,
                                                 final VortexAggregatePolicy policy) {
      final TaskletAggregationRequest<TInput, TOutput> taskletAggregationRequest =
          new TaskletAggregationRequest<>(aggregateFunctionId, aggregateFunction, function, policy);
  
      // The send is synchronous such that we make sure that the aggregate function is sent to the
      // target worker before attempting to launch an aggregateable tasklet on it.
      vortexRequestor.send(reefTask, taskletAggregationRequest);
    }
docs: Sends an {@link VortexAggregateFunction} and its {@link VortexFunction} to a
  {@link org.apache.reef.vortex.evaluator.VortexWorker}.