new_contents: """empty message
  
  Revision ID: 2316c9808a5
  Revises: 26fbbffb991
  Create Date: 2015-04-16 13:46:41.849087
  
  """
  
  # revision identifiers, used by Alembic.
  revision = '2316c9808a5'
  down_revision = '26fbbffb991'
  
  from alembic import op
  import sqlalchemy as sa
  
  
  def upgrade():
      ### commands auto generated by Alembic - please adjust! ###
      op.add_column('courses', sa.Column('homepage', sa.Text(), nullable=True))
      op.add_column('teachers', sa.Column('avatar', sa.Integer(), nullable=True))
      op.add_column('teachers', sa.Column('homepage', sa.Text(), nullable=True))
      op.create_foreign_key(None, 'teachers', 'image_store', ['avatar'], ['id'])
      op.add_column('users', sa.Column('homepage', sa.Text(), nullable=True))
      ### end Alembic commands ###
  
  
  def downgrade():
      ### commands auto generated by Alembic - please adjust! ###
      op.drop_column('users', 'homepage')
      op.drop_constraint(None, 'teachers', type_='foreignkey')
      op.drop_column('teachers', 'homepage')
      op.drop_column('teachers', 'avatar')
      op.drop_column('courses', 'homepage')
      ### end Alembic commands ###
  
subject: add DB migration