content: from django.apps import apps
  
  
  def get_prerequisite_model(queryset):
      """
      Return any prerequisite model that must be created prior to creating
      an instance of the current model.
      """
      if not queryset.exists():
          for prereq in getattr(queryset.model, 'prerequisite_models', []):
              model = apps.get_model(prereq)
              if not model.objects.exists():
                  return model
  