code: def evaluate(
      self, trials: list[FrozenTrial], study_direction: StudyDirection
  ) -> float:
      return self._constant
  
file_path: optuna/tests/terminator_tests/test_terminator.py
imports: from __future__ import annotations
  import pytest
  from optuna.study._study_direction import StudyDirection
  from optuna.study.study import create_study
  from optuna.terminator import BaseImprovementEvaluator
  from optuna.terminator import StaticErrorEvaluator
  from optuna.terminator import Terminator
  from optuna.terminator.improvement.evaluator import BestValueStagnationEvaluator
  from optuna.trial import FrozenTrial
label_desc: Use image node_id 2 for calling the _StaticImprovementEvaluator obj's underlying member method code with example usage: obj.evaluate(trials, study_direction) and returns: self