code: def _set_object_self(self, obj):
          
          from nefertari.elasticsearch import ES
          location = self.request.path_url
          route_kwargs = {}
  
          """ Check for parents """
          if self.request.matchdict:
              route_kwargs.update(self.request.matchdict)
          try:
              type_, obj_pk = obj['_type'], obj['_pk']
          except KeyError:
              return
          resource = (self.model_collections.get(type_) or
                      self.model_collections.get(ES.src2type(type_)))
          if resource is not None:
              route_kwargs.update({resource.id_name: obj_pk})
              location = self.request.route_url(
                  resource.uid, **route_kwargs)
          obj.setdefault('_self', location)
docs: Add '_self' key value to :obj: dict.