code: def drop_bel_namespace(self) -> Optional[Namespace]:
          
          namespace = self._get_default_namespace()
  
          if namespace is not None:
              for entry in tqdm(namespace.entries, desc=f'deleting entries in {self._get_namespace_name()}'):
                  self.session.delete(entry)
              self.session.delete(namespace)
  
              log.info('committing deletions')
              self.session.commit()
              return namespace
docs: Remove the default namespace if it exists.