code: def partition_expiration(self):
          
          warnings.warn(
              "This method will be deprecated in future versions. Please use "
              "Table.time_partitioning.expiration_ms instead.",
              PendingDeprecationWarning,
              stacklevel=2,
          )
          if self.time_partitioning is not None:
              return self.time_partitioning.expiration_ms
docs: Union[int, None]: Expiration time in milliseconds for a partition.
  
          If :attr:`partition_expiration` is set and :attr:`type_` is
          not set, :attr:`type_` will default to
          :attr:`~google.cloud.bigquery.table.TimePartitioningType.DAY`.