code: def get_instance(
      self, instance_id: Union[str, int]
  ) -> Optional[dict]:
      instances = self.get_instances()
      for instance in instances:
          if instance["id"] == int(instance_id):
              return instance
      return None
  
file_path: dstack/src/dstack/_internal/core/backends/vastai/api_client.py
imports: import shlex
  import threading
  import time
  from typing import List, Optional, Union
  import requests
  from requests.adapters import HTTPAdapter, Retry
  import dstack._internal.server.services.docker
  from dstack._internal.core.errors import NoCapacityError
  from dstack._internal.core.models.configurations import RegistryAuth
label_desc: Use image node_id 6 for calling the VastAIAPIClient obj's underlying member method code with example usage: obj.get_instance(instance_id) and returns: None, instance