docs: def sample_ids_in_class(self, class_id):
          """
          Returns a list of sample ids belonging to a given class.
  
          Parameters
          ----------
          class_id : str
              class id to query.
  
          Returns
          -------
          subset_ids : list
              List of sample ids belonging to a given class.
  
          """
  
          # subset_ids = [sid for sid in self.keys if self.classes[sid] == class_id]
          subset_ids = self.keys_with_value(self.classes, class_id)
          return subset_ids