code: def _get_instances(cls, path, context=None, site=None, language=None):
          
          backend_context = {'view_context': context }
  
          for model in cls._meta.models.values():
              for instance in model.objects.get_instances(path, site, language, backend_context) or []:
                  if hasattr(instance, '_process_context'):
                      instance._process_context(backend_context)
                  yield instance
docs: A sequence of instances to discover metadata. 
              Each instance from each backend is looked up when possible/necessary.
              This is a generator to eliminate unnecessary queries.