code: def read_exclusions(exclusions_file):
      """Reads a CSV file of excluded timestamps.
      Args:
        exclusions_file: A file object containing a csv of video-id,timestamp.
      Returns:
        A set of strings containing excluded image keys, e.g. "aaaaaaaaaaa,0904",
        or an empty set if exclusions file is None.
      """
      excluded = set()
      if exclusions_file:
          with pathmgr.open(exclusions_file, "r") as f:
              reader = csv.reader(f)
              for row in reader:
                  assert len(row) == 2, (
                      "Expected only 2 columns, got: " + row
                  )
                  excluded.add(make_image_key(row[0], row[1]))
      return excluded
  
file_path: SlowFast/slowfast/utils/ava_eval_helper.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import csv
  import logging
  import pprint
  import time
  from collections import defaultdict
  import numpy
  import slowfast.utils.distributed
  from ava_evaluation import object_detection_evaluation, standard_fields
  from slowfast.utils.env import pathmgr
label_desc: Use image node_id 3 for calling a global function with example usage: read_exclusions(exclusions_file) and returns: excluded