code: def get_instance(cls, address: str, config: Dict = None):
      type_addr = (cls, address)
      if type_addr not in cls._instances:
          inst = cls._instances[type_addr] = cls(config, address)
      else:
          inst = cls._instances[type_addr]
      return inst
  
file_path: mars/mars/services/core.py
imports: import abc
  import asyncio
  import enum
  import importlib
  import inspect
  import warnings
  from typing import Dict, Iterable, List, Union
label_desc: Use image node_id 2 for calling the AbstractService obj's underlying member method code with example usage: obj.get_instance(cls, address, config) and returns: inst