old_contents: # revision identifiers, used by Alembic.
  revision = '8a8e921cb88'
  down_revision = '16f9f28f0ea3'
  
  from alembic import op
  import sqlalchemy as sa
  
  
  def upgrade():
      op.add_column('flights', sa.Column('scoring_start_time', sa.DateTime(), nullable=True))
      op.add_column('flights', sa.Column('scoring_end_time', sa.DateTime(), nullable=True))
  
  
  def downgrade():
      op.drop_column('flights', 'scoring_start_time')
      op.drop_column('flights', 'scoring_end_time')
  
new_contents: # revision identifiers, used by Alembic.
  revision = '8a8e921cb88'
  down_revision = '54d325616135'
  
  from alembic import op
  import sqlalchemy as sa
  
  
  def upgrade():
      op.add_column('flights', sa.Column('scoring_start_time', sa.DateTime(), nullable=True))
      op.add_column('flights', sa.Column('scoring_end_time', sa.DateTime(), nullable=True))
  
  
  def downgrade():
      op.drop_column('flights', 'scoring_start_time')
      op.drop_column('flights', 'scoring_end_time')
  
subject: fix parent revision number...