code: def __init__(self, init_lr, gamma, iter_interval):
      self.init_lr = init_lr
      self.gamma = gamma
      self.iter_interval = iter_interval
  
file_path: nnabla/python/test/utils/learning_rate_scheduler/test_exponential_scheduler.py
imports: import pytest
  from learning_rate_scheduler_test_utils import scheduler_tester
  import nnabla.utils.learning_rate_scheduler
label_desc: Use image node_id 1 to create a new RefExponential object from inherited base classes: object with example: obj = RefExponential(init_lr, gamma, iter_interval)