code: def _get_id(self, id_, pkg_name):
          
          collection = JSONClientValidated('id',
                                           collection=pkg_name + 'Ids',
                                           runtime=self._runtime)
          try:
              result = collection.find_one({'aliasIds': {'$in': [str(id_)]}})
          except errors.NotFound:
              return id_
          else:
              return Id(result['_id'])
docs: Returns the primary id given an alias.
  
          If the id provided is not in the alias table, it will simply be
          returned as is.
  
          Only looks within the Id Alias namespace for the session package