code: def _downgrade_v1(op):
      
      # Drop indices before batch
      # This is to prevent index collision when creating the temp table
      op.drop_index('ix_futures_contracts_root_symbol')
      op.drop_index('ix_futures_contracts_symbol')
  
      # Execute batch op to allow column modification in SQLite
      with op.batch_alter_table('futures_contracts') as batch_op:
  
          # Rename 'multiplier'
          batch_op.alter_column(column_name='multiplier',
                                new_column_name='contract_multiplier')
  
          # Delete 'tick_size'
          batch_op.drop_column('tick_size')
  
      # Recreate indices after batch
      op.create_index('ix_futures_contracts_root_symbol',
                      table_name='futures_contracts',
                      columns=['root_symbol'])
      op.create_index('ix_futures_contracts_symbol',
                      table_name='futures_contracts',
                      columns=['symbol'],
                      unique=True)
docs: Downgrade assets db by removing the 'tick_size' column and renaming the
      'multiplier' column.