code: def _get_buffer(self, index):
      assert index != INVALID_BUFFER_INDEX
      return self.all_buffers[index]
  
imports: import torch
  from deepspeed import comm
  from deepspeed.utils.logging import logger
  from deepspeed.runtime.swap_tensor.utils import swap_out_tensors, SwapBuffer
  from deepspeed.accelerator import get_accelerator
label_desc: Use image node_id 16 for calling the AsyncTensorSwapper obj's underlying member method code with example usage: obj._get_buffer(index) and returns: self