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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def seek_to_beginning(self, *partitions):
 """Seek to the oldest available offset for partitions. Arguments: *partitions: Optionally provide specific TopicPartitions, otherwise default to all assigned partitions. Raises: AssertionError: If any partition is not currently assigned, or if no partitions are assigned. """

        if not all([isinstance(p, TopicPartition) for p in partitions]):
            raise TypeError('partitions must be TopicPartition namedtuples')
        if not partitions:
            partitions = self._subscription.assigned_partitions()
            assert partitions, 'No partitions are currently assigned'
        else:
            for p in partitions:
                assert p in self._subscription.assigned_partitions(), 'Unassigned partition'

        for tp in partitions:
            log.debug("Seeking to beginning of partition %s", tp)
            self._subscription.need_offset_reset(tp, OffsetResetStrategy.EARLIEST)