code: def service_name(self, service_name: t.Optional[str]) -> None:
      self._service_name_var.set(service_name)
  
imports: from __future__ import annotations
  import contextlib
  import contextvars
  import os
  import typing
  from abc import ABC
  from abc import abstractmethod
  from typing import TYPE_CHECKING
  import attr
  import starlette.datastructures
  from .utils.http import Cookie
label_desc: Use image node_id 7 for calling the _ServiceTraceContext obj's underlying member method code with example usage: obj.service_name(service_name) without return types