new_contents: from __future__ import print_function
  import json
  import random
  import string
  
  def lambda_handler(event, context):
      characters = string.ascii_letters + '!@#$%^&*()[]{}'
      length = event['length']
      return ''.join(random.SystemRandom().choice(characters) for _ in range(length))
  
subject: Create random_generator.py