code: def save(
      obj,
      f: Union[str, os.PathLike, BinaryIO, IO[bytes]],
      pickle_module=pickle,
      pickle_protocol=DEFAULT_PROTOCOL,
      _use_new_zipfile_serialization=True,
      encryption_key: Optional[str] = None,
  ) -> None:
      """
      Save method that will be used to replace torch.save.
  
      Only used in patched torch.
  
      :param encryption_key: Optional[str] = None. If set to None, the original
             torch.save will be invoked.  Otherwise, the content will be encrypted
             before writing it to final destination.
      """
      if encryption_key is None:
          return torch.old_save(
              obj,
              f,
              pickle_module=pickle_module,
              pickle_protocol=pickle_protocol,
              _use_new_zipfile_serialization=_use_new_zipfile_serialization,
          )
      buffer = io.BytesIO()
      encrypted_buffer = io.BytesIO()
      torch.old_save(
          obj,
          buffer,
          pickle_module=pickle_module,
          pickle_protocol=pickle_protocol,
          _use_new_zipfile_serialization=_use_new_zipfile_serialization,
      )
      encryptor = _buf_operator(encryption_key)
      encryptor.encrypt_buffer(buffer, encrypted_buffer)
      with _open_file_or_buffer(f, "wb") as opened_file:
          opened_file.write(encrypted_buffer.getvalue())
      buffer.close()
      encrypted_buffer.close()
      return
  
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 a global function with example usage: save(obj, f, pickle_module, pickle_protocol, _use_new_zipfile_serialization, encryption_key) and returns: torch