new_contents: """add published field to category model
  
  Revision ID: 3d8cf74c2de4
  Revises: None
  Create Date: 2015-09-21 22:27:36.166147
  
  """
  
  # revision identifiers, used by Alembic.
  revision = '3d8cf74c2de4'
  down_revision = None
  
  from alembic import op
  import sqlalchemy as sa
  
  
  def upgrade():
      op.add_column('category', sa.Column('published', sa.Boolean(),
                                          nullable=False))
  
  
  def downgrade():
      op.drop_column('category', 'published')
  
subject: add db migration for category model