code: def external_ip(self, node_id):
      with self.lock:
          return self.mock_nodes[node_id].external_ip
  
imports: import re
  import threading
  from subprocess import CalledProcessError
  from typing import Callable, Dict, List, Optional
  from ray.autoscaler.node_provider import NodeProvider
label_desc: Use image node_id 8 for calling the MockProvider obj's underlying member method code with example usage: obj.external_ip(node_id) and returns: self