code: def test_cached_key():
      first_validator = RSASignatureValidator()
      second_validator = RSASignatureValidator()
      assert (
          first_validator.local_public_key
          == second_validator.local_public_key
      )
  
      third_validator = RSASignatureValidator(RSAPrivateKey())
      assert (
          first_validator.local_public_key
          != third_validator.local_public_key
      )
  
file_path: hivemind/tests/test_dht_crypto.py
imports: import dataclasses
  import multiprocessing
  import pickle
  import pytest
  import hivemind
  from hivemind.dht.crypto import RSASignatureValidator
  from hivemind.dht.node import DHTNode
  from hivemind.dht.validation import DHTRecord
  from hivemind.utils.crypto import RSAPrivateKey
  from hivemind.utils.timed_storage import get_dht_time
label_desc: Use image node_id 2 for calling a global function with example usage: test_cached_key() without return types