How to use the mpipool.core.MPIPoolException function in mpipool

# Check if message is special type containing new function
            # to be applied
            if isinstance(task, _function_wrapper):
                self.function = task.function
                if self.debug:
                    print("Worker {0} replaced its task function: {1}."
                          .format(self.rank, self.function))
                continue

            # If not a special message, just run the known function on
            # the input and return it asynchronously.
            try:
                result = self.function(task)
            except:
                tb = traceback.format_exc()
                self.comm.isend(MPIPoolException(tb), dest=0, tag=status.tag)
                return
            if self.debug:
                print("Worker {0} sending answer {1} with tag {2}."
                      .format(self.rank, result, status.tag))
            self.comm.isend(result, dest=0, tag=status.tag)

print("Sent task {0} to worker {1} with tag {2}."
                          .format(task, worker, i))
                r = self.comm.isend(task, dest=worker, tag=i)
                requests.append(r)

            MPI.Request.waitall(requests)

            # Now wait for the answers.
            results = []
            for i in range(ntask):
                worker = i % self.size + 1
                if self.debug:
                    print("Master waiting for worker {0} with tag {1}"
                          .format(worker, i))
                result = self.comm.recv(source=worker, tag=i)
                if isinstance(result, MPIPoolException):
                    print("One of the MPIPool workers failed with the "
                          "exception:")
                    print(result.traceback)
                    raise result

                if callback is not None:
                    callback(result)

                results.append(result)

            return results

        else:
            # Perform load-balancing. The order of the results are likely to
            # be different from the previous case.
            for i, task in enumerate(tasks[0:self.size]):