This task's dependencies:

        * :py:class:`~.AggregateArtists` or
        * :py:class:`~.AggregateArtistsSpark` if :py:attr:`~/.Top10Artists.use_spark` is set.

        :return: object (:py:class:`luigi.task.Task`)

def requires(self):
        """
        This task's dependencies:

        * :py:class:`~.AggregateArtists` or
        * :py:class:`~.AggregateArtistsSpark` if :py:attr:`~/.Top10Artists.use_spark` is set.

        :return: object (:py:class:`luigi.task.Task`)
        """
        if self.use_spark:
            return AggregateArtistsSpark(self.date_interval)
        else:
            return AggregateArtists(self.date_interval)