@classmethod
  def AllocateAssetIds(cls, client, user_id, num_ids, callback):
    id_seq_key = cls._table.GetColumn('asset_id_seq').key

    def _OnUpdateIdSeq(result):
      last_id = result.return_values[id_seq_key]
      first_id = last_id - num_ids
      callback(first_id)

    client.UpdateItem(table=cls._table.name,
                      key=db_client.DBKey(hash_key=user_id, range_key=None),
                      attributes={id_seq_key: db_client.UpdateAttr(value=num_ids, action='ADD')},
                      return_values='UPDATED_NEW', callback=_OnUpdateIdSeq)
Allocates 'num_ids' new ids from the 'asset_id_seq' column in a
dataset/ETHPy150Open viewfinderco/viewfinder/backend/db/user.py/User.AllocateAssetIds