**** CubicPower OpenStack Study ****
def upgrade(migrate_engine):
meta = sql.MetaData()
meta.bind = migrate_engine
token = sql.Table('token', meta, autoload=True)
idx = sql.Index('ix_token_valid', token.c.valid)
idx.drop(migrate_engine)
**** CubicPower OpenStack Study ****
def downgrade(migrate_engine):
meta = sql.MetaData()
meta.bind = migrate_engine
token = sql.Table('token', meta, autoload=True)
idx = sql.Index('ix_token_valid', token.c.valid)
idx.create(migrate_engine)