docs: def _update_metadata(self, archive_name, archive_metadata):
          """
          Appends the updated_metada dict to the Metadata Attribute list
  
          Parameters
          ----------
          archive_name: str
  
              ID of archive to update
  
          updated_metadata: dict
  
              dictionary of metadata keys and values to update. If the value
              for a particular key is `None`, the key is removed.
  
          """
  
          archive_metadata_current = self._get_archive_metadata(archive_name)
          archive_metadata_current.update(archive_metadata)
          for k, v in archive_metadata_current.items():
              if v is None:
                  del archive_metadata_current[k]
  
          # add the updated archive_metadata object to Dynamo
          self._table.update_item(
              Key={'_id': archive_name},
              UpdateExpression="SET archive_metadata = :v",
              ExpressionAttributeValues={':v': archive_metadata_current},
              ReturnValues='ALL_NEW')