text: #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  from sqlalchemy import Column
  from sqlalchemy import MetaData, Integer, Table, ForeignKey
  
  
  def upgrade(migrate_engine):
      """Add allocated_id to the reservations table."""
      meta = MetaData()
      meta.bind = migrate_engine
  
      reservations = Table('reservations', meta, autoload=True)
      Table('quotas', meta, autoload=True)
      allocated_id = Column('allocated_id', Integer, ForeignKey('quotas.id'),
                            nullable=True)
      reservations.create_column(allocated_id)
      usage_id = reservations.c.usage_id
      usage_id.alter(nullable=True)
  