docs: def is_existing_object(did):
      """Return True if PID is for an object for which science bytes are stored locally.
  
      This excludes SIDs and PIDs for unprocessed replica requests, remote or non-existing
      revisions of local replicas and objects aggregated in Resource Maps.
  
      """
      return d1_gmn.app.models.ScienceObject.objects.filter(pid__did=did).exists()