code: def before_epoch(self, runner):
      if self._before_epoch:
          torch.cuda.empty_cache()
  
file_path: lavis/lavis/common/annotator/uniformer/mmcv/runner/hooks/memory.py
imports: import torch
  from .hook import HOOKS, Hook
label_desc: Use image node_id 3 for calling the EmptyCacheHook obj's underlying member method code with example usage: obj.before_epoch(runner) without return types