code: def assert_allowed(request, level, pid):
      
      if not d1_gmn.app.models.ScienceObject.objects.filter(pid__did=pid).exists():
          raise d1_common.types.exceptions.NotFound(
              0,
              'Attempted to perform operation on non-existing object. pid="{}"'.format(
                  pid
              ),
          )
      if not is_allowed(request, level, pid):
          raise d1_common.types.exceptions.NotAuthorized(
              0,
              'Operation is denied. level="{}", pid="{}", active_subjects="{}"'.format(
                  level_to_action(level), pid, format_active_subjects(request)
              ),
          )
docs: Assert that one or more subjects are allowed to perform action on object.
  
      Raise NotAuthorized if object exists and subject is not allowed. Raise NotFound if
      object does not exist.