text: from sqlalchemy import *
  from migrate import *
  
  
  from migrate.changeset import schema
  pre_meta = MetaData()
  post_meta = MetaData()
  article = Table('article', post_meta,
      Column('id', Integer, primary_key=True, nullable=False),
      Column('title', String(length=1000)),
      Column('doi', String(length=100)),
      Column('journal', String(length=1000)),
      Column('score', Integer),
      Column('abstract', String(length=10000)),
      Column('default_set', Boolean, nullable=False),
      Column('pub_date', Integer),
  )
  
  
  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['article'].columns['pub_date'].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['article'].columns['pub_date'].drop()
  