docs: def command_drop_tables(self, meta_name=None):
          '''
          Drops all tables without dropping a database::
  
              ./manage.py sqla:drop_tables [meta_name]
          '''
          answer = six.moves.input(u'All data will lost. Are you sure? [y/N] ')
  
          if answer.strip().lower()!='y':
              sys.exit('Interrupted')
  
          def _drop_metadata_tables(metadata):
              table = next(six.itervalues(metadata.tables), None)
              if table is None:
                  print('Failed to find engine')
              else:
                  engine = self.session.get_bind(clause=table)
                  drop_everything(engine)
                  print('Done')
  
          if isinstance(self.metadata, MetaData):
              print('Droping tables... ', end='')
              _drop_metadata_tables(self.metadata)
          else:
              for current_meta_name, metadata in self.metadata.items():
                  if meta_name not in (current_meta_name, None):
                      continue
                  print('Droping tables for {}... '.format(current_meta_name),
                        end='')
                  _drop_metadata_tables(metadata)