code: def main():
      This main function implements the CLI"""
      parser = argparse.ArgumentParser(description='Do something awesome')
      parser.add_argument('input_list', nargs='+',
                          type=str, default=sys.stdin)
      parser.add_argument('-o', '--outfile', nargs='?',
                          type=argparse.FileType('w'), default=sys.stdout)
      args = parser.parse_args()
  
      input_list = args.input_list
      print '\n'.join(get_ips_from_cidr_subnets(input_list))
docs: This main function implements the CLI