code: def decrypt_buffer(self, buffer, decrypted_buffer):
      decrypted_content = self.secret_key.decrypt(buffer.getvalue())
      decrypted_buffer.write(decrypted_content)
  
imports: import torch
  from torch.utils.data import Dataset
  import io
  import os
  import pathlib
  from cryptography.fernet import Fernet
  from typing import BinaryIO, Union, IO, Optional
  import pickle
  from bigdl.nano.utils.common import invalidInputError
label_desc: Use image node_id 3 for calling the _buf_operator obj's underlying member method code with example usage: obj.decrypt_buffer(buffer, decrypted_buffer) without return types