code: def sign(self, data: bytes) -> bytes:
      ...
  
imports: from __future__ import annotations
  import base64
  import threading
  from abc import ABC, abstractmethod
  from cryptography import exceptions
  from cryptography.hazmat.primitives import hashes, serialization
  from cryptography.hazmat.primitives.asymmetric import padding, rsa
label_desc: Use image node_id 1 for calling the PrivateKey obj's underlying member method code with example usage: obj.sign(data) without return types