code: def get_lr(self, runner, base_lr):
      progress = runner.epoch if self.by_epoch else runner.iter
      return base_lr * self.gamma**progress
  
imports: import numbers
  from math import cos, pi
  import annotator.uniformer.mmcv
  from .hook import HOOKS, Hook
label_desc: Use image node_id 2 for calling the ExpLrUpdaterHook obj's underlying member method code with example usage: obj.get_lr(runner, base_lr) and returns: unknown