code: def stop(self):
      super().stop()
      self.sc.stop()
      self.sc = None
  
imports: import sys
  import os
  import pyspark
  import pyspark.sql
  import orjson
  from typing import Optional
  from hail.expr.table_type import ttable
  from hail.fs.hadoop_fs import HadoopFS
  from hail.ir.renderer import CSERenderer
  from hail.table import Table
  from hailtop.aiotools.router_fs import RouterAsyncFS
  from hailtop.aiotools.validators import validate_file
  from .py4j_backend import Py4JBackend
  from .backend import local_jar_information
label_desc: Use image node_id 3 for calling the SparkBackend obj's underlying member method code with example usage: obj.stop() without return types