def add_eval_case(self, app_name: str, eval_set_id: str, eval_case: EvalCase):
    """Adds the given EvalCase to an existing EvalSet identified by app_name and eval_set_id.

    Raises:
      NotFoundError: If the eval set is not found.
    """
    eval_case_id = eval_case.eval_id
    self._validate_id(id_name="Eval Case Id", id_value=eval_case_id)

    eval_set = self.get_eval_set(app_name, eval_set_id)

    if not eval_set:
      raise NotFoundError(f"Eval set `{eval_set_id}` not found.")

    if [x for x in eval_set.eval_cases if x.eval_id == eval_case_id]:
      raise ValueError(
          f"Eval id `{eval_case_id}` already exists in `{eval_set_id}`"
          " eval set.",
      )

    eval_set.eval_cases.append(eval_case)

    eval_set_file_path = self._get_eval_set_file_path(app_name, eval_set_id)
    self._write_eval_set(eval_set_file_path, eval_set)
Adds the given EvalCase to an existing EvalSet identified by app_name and eval_set_id.

    Raises:
      NotFoundError: If the eval set is not found.
    
src/google/adk/evaluation/local_eval_sets_manager.py