code: def validate_files(input_files):
      """
      The valid files will have name: <class_name>_<split>.txt. We want to remove
      all the other files from the input.
      """
      output_files = []
      for item in input_files:
          if len(item.split("/")[-1].split("_")) == 2:
              output_files.append(item)
      return output_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 2 for calling a global function with example usage: validate_files(input_files) and returns: output_files