code: def test_build_step_with_fixed_gamma_scheduler(self):
      config = self._get_valid_config()
      scheduler = build_param_scheduler(config)
      self.assertTrue(
          isinstance(scheduler, StepWithFixedGammaParamScheduler)
      )
  
file_path: ClassyVision/test/optim_param_scheduler_step_with_fixed_gamma_test.py
imports: import copy
  import unittest
  from classy_vision.optim.param_scheduler import build_param_scheduler, StepWithFixedGammaParamScheduler
label_desc: Use image node_id 4 for calling the TestStepWithFixedGammaScheduler obj's underlying member method code with example usage: obj.test_build_step_with_fixed_gamma_scheduler() without return types