code: def forward(self, *args, **kwargs):
      if self._use_checkpoint:
          return checkpoint(self._forward, *args, **kwargs)
      else:
          return self._forward(*args, **kwargs)
  
file_path: ColossalAI/tests/kit/model_zoo/custom/base.py
imports: import torch.nn
  from torch.utils.checkpoint import checkpoint
label_desc: Use image node_id 3 for calling the CheckpointModule obj's underlying member method code with example usage: obj.forward() and returns: checkpoint, self