content: from mmcv.runner import OPTIMIZERS
  from torch.optim import SGD
  
  
  @OPTIMIZERS.register_module()
  class CopyOfSGD(SGD):
      """A clone of torch.optim.SGD.
  
      A customized optimizer could be defined like CopyOfSGD. You may derive from
      built-in optimizers in torch.optim, or directly implement a new optimizer.
      """
  