code: def _run_down(self, path, migration, pretend=False):
          
          migration_file = migration['migration']
  
          instance = self._resolve(path, migration_file)
  
          if pretend:
              return self._pretend_to_run(instance, 'down')
  
          instance.down()
  
          self._repository.delete(migration)
  
          self._note('<info>✓ Rolled back</info> %s' % migration_file)
docs: Run "down" a migration instance.