code: def _completed_rung_key(rung: int) -> str:
      return "completed_rung_{}".format(rung)
  
file_path: optuna/optuna/pruners/_successive_halving.py
imports: import math
  from typing import List
  from typing import Optional
  from typing import Union
  import optuna
  from optuna.pruners._base import BasePruner
  from optuna.study._study_direction import StudyDirection
  from optuna.trial._state import TrialState
label_desc: Use image node_id 3 for calling a global function with example usage: _completed_rung_key(rung) and returns: str