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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 copy_part_from_key(self, src_bucket_name, src_key_name, part_num, start=None, end=None):
 """ Copy another part of this MultiPart Upload. :type src_bucket_name: string :param src_bucket_name: Name of the bucket containing the source key :type src_key_name: string :param src_key_name: Name of the source key :type part_num: int :param part_num: The number of this part. :type start: int :param start: Zero-based byte offset to start copying from :type end: int :param end: Zero-based byte offset to copy to """

        if part_num < 1:
            raise ValueError('Part numbers must be greater than zero')
        query_args = 'uploadId=%s&partNumber=%d' % (self.id, part_num)
        if start is not None and end is not None:
            rng = 'bytes=%s-%s' % (start, end)
            provider = self.bucket.connection.provider
            headers = {provider.copy_source_range_header: rng}
        else:
            headers = None
        return self.bucket.copy_key(self.key_name, src_bucket_name,
                                    src_key_name, storage_class=None,
                                    headers=headers,
                                    query_args=query_args)