docs: def as_partition(self, partition=0, **kwargs):
          """Return a new PartitionIdentity based on this Identity.
  
          :param partition: Integer partition number for PartitionObjectNumber
          :param kwargs:
  
          """
  
          assert isinstance(self._name, Name), "Wrong type: {}".format(type(self._name))
          assert isinstance(self._on, DatasetNumber), "Wrong type: {}".format(type(self._on))
  
          name = self._name.as_partition(**kwargs)
          on = self._on.as_partition(partition)
  
          return PartitionIdentity(name, on)