docs: def head_object(request, pid):
      """MNRead.describe(session, did) → DescribeResponse."""
      sciobj = d1_gmn.app.models.ScienceObject.objects.get(pid__did=pid)
      response = django.http.HttpResponse()
      d1_gmn.app.views.headers.add_sciobj_properties_headers_to_response(response, sciobj)
      d1_gmn.app.event_log.log_read_event(pid, request)
      return response