Possible fix for error on travis

        worker_pool = mp.Pool(processes=1)

    log("Spawning workers now.", self.verbosity)

    metadata_rows = []

    data_iterator = zip(

        it.repeat((self, shard_size, input_type, data_dir)),

    def wrap_with_shard_metadata(iterator):

      for item in iterator:

        yield ((self, shard_size, input_type, data_dir), item)

    data_iterator = wrap_with_shard_metadata(

        enumerate(load_data(input_files, shard_size, self.verbosity)))

    # Turns out python map is terrible and exhausts the generator as given.

    # Solution seems to be to to manually pull out N elements from iterator,