ater than one, the iterables will be chopped into
                chunks of size chunksize and submitted to the process pool.
                If set to one, the items in the list will be sent one at a time.

        Returns:
            An iterator equivalent to: map(func, *iterables) but the calls may
            be evaluated out-of-order.

        Raises:
            TimeoutError: If the entire result iterator could not be generated
                before the given timeout.
            Exception: If fn(*args) raises for any values.
        r1