code: def validate_chunk_width(chunk_width):
      """Validate a chunk-width string , returns boolean.
      Expected to be a string representing either an integer, like '20',
      or a comma-separated list of integers like '20,30,16'"""
      if not isinstance(chunk_width, str):
          return False
      a = chunk_width.split(",")
      assert len(a) != 0  # would be code error
      for elem in a:
          try:
              i = int(elem)
              if i < 1 and i != -1:
                  return False
          except:
              return False
      return True
  
imports: from __future__ import division
  import argparse
  import glob
  import logging
  import os
  import math
  import re
  import shutil
  import libs.common
  from libs.nnet3.train.dropout_schedule import *
  import unittest
label_desc: Use image node_id 6 for calling a global function with example usage: validate_chunk_width(chunk_width) and returns: True, False, False, False