code: def test_signing_key() -> None:
      # we should keep our representation in hex ASCII
  
      # first convert the string representation into a key
      test_signing_key = SyftSigningKey.from_string(
          test_signing_key_string
      )
      assert isinstance(test_signing_key, SyftSigningKey)
  
      # make sure it converts back to the same string
      assert str(test_signing_key) == test_signing_key_string
  
      # make a second one and verify that its equal
      test_signing_key_2 = SyftSigningKey.from_string(
          test_signing_key_string
      )
      assert test_signing_key == test_signing_key_2
  
      # get the derived verify key
      test_verify_key = test_signing_key.verify_key
      assert isinstance(test_verify_key, SyftVerifyKey)
  
      # make sure both types provide the verify key as a string
      assert test_verify_key_string == test_verify_key.verify
      assert test_verify_key_string == test_signing_key.verify
  
      # make sure that we don't print signing key but instead the verify key
      assert SIGNING_KEY_FOR in test_signing_key.__repr__()
      assert test_verify_key_string in test_signing_key.__repr__()
  
      # get another verify key from the same string and make sure its equal
      test_verify_key_2 = SyftVerifyKey.from_string(
          test_verify_key_string
      )
      assert test_verify_key == test_verify_key_2
  
imports: from typing import Any
  from typing import Dict
  from nacl.exceptions import BadSignatureError
  import numpy
  import pytest
  from result import Ok
  import syft
  from syft.client.api import SignedSyftAPICall
  from syft.client.api import SyftAPICall
  from syft.node.credentials import SIGNING_KEY_FOR
  from syft.node.credentials import SyftSigningKey
  from syft.node.credentials import SyftVerifyKey
  from syft.node.worker import Worker
  from syft.service.action.action_object import ActionObject
  from syft.service.action.action_store import DictActionStore
  from syft.service.context import AuthedServiceContext
  from syft.service.queue.queue_stash import QueueItem
  from syft.service.response import SyftAttributeError
  from syft.service.response import SyftError
  from syft.service.user.user import User
  from syft.service.user.user import UserCreate
  from syft.service.user.user import UserView
  from syft.service.user.user_service import UserService
  from syft.types.uid import UID
label_desc: Use image node_id 1 for calling a global function with example usage: test_signing_key() without return types