code: def get_data_files(split, data_source_dir):
      data_dir = f"{data_source_dir}/ImageSets/Main"
      assert g_pathmgr.exists(
          data_dir
      ), "Data: {} doesn't exist".format(data_dir)
      test_data_files = glob(os.path.join(data_dir, "*_test.txt"))
      test_data_files = validate_files(test_data_files)
      train_data_files = glob(os.path.join(data_dir, "*_trainval.txt"))
      if len(test_data_files) == 0:
          # For VOC2012 dataset, we have trainval, val and train data.
          train_data_files = glob(os.path.join(data_dir, "*_train.txt"))
          test_data_files = glob(os.path.join(data_dir, "*_val.txt"))
      test_data_files = validate_files(test_data_files)
      train_data_files = validate_files(train_data_files)
      data_files = (
          train_data_files if (split == "train") else test_data_files
      )
      assert len(train_data_files) == len(
          test_data_files
      ), "Missing classes"
      return data_files
  
file_path: vissl/vissl/data/datasets/pascal_voc.py
imports: import logging
  import os
  from glob import glob
  import numpy
  from iopath.common.file_io import g_pathmgr
  from vissl.utils.io import makedir, save_file
label_desc: Use image node_id 3 for calling a global function with example usage: get_data_files(split, data_source_dir) and returns: data_files