code: def open_output_file(self):
      if self.output_file is not None:
          self.output_fd = open(self.output_file, "w")
  
imports: import os
  import sys
  import argparse
  import json
  import itertools
  import subprocess
  import shutil
  from test_ds_aio_utils import refine_integer_value
  from perf_sweep_utils import READ_OP_DESC, WRITE_OP_DESC, BENCH_LOG_DIR, READ_IO_DIR, WRITE_IO_DIR, READ_LOG_DIR, WRITE_LOG_DIR
label_desc: Use image node_id 6 for calling the Job obj's underlying member method code with example usage: obj.open_output_file() without return types