text: from sqlalchemy import *
  from migrate import *
  
  
  from migrate.changeset import schema
  pre_meta = MetaData()
  post_meta = MetaData()
  person = Table('person', post_meta,
      Column('id', Integer, primary_key=True, nullable=False),
      Column('sid', String(length=7)),
      Column('last', String(length=120)),
      Column('first', String(length=120)),
      Column('color', String(length=120)),
  )
  
  
  def upgrade(migrate_engine):
      # Upgrade operations go here. Don't create your own engine; bind
      # migrate_engine to your metadata
      pre_meta.bind = migrate_engine
      post_meta.bind = migrate_engine
      post_meta.tables['person'].columns['color'].create()
  
  
  def downgrade(migrate_engine):
      # Operations to reverse the above upgrade go here.
      pre_meta.bind = migrate_engine
      post_meta.bind = migrate_engine
      post_meta.tables['person'].columns['color'].drop()
  