input: 
  import random
  import string
  
  def random_string(length: int) -> str:
      """ Generate a random string of given length.
      >>> random_string(6)
      'abcxyz'
      >>> random_string(6)
      'qwerty'
      """
      letters = string.ascii_lowercase
      return ''.join(random.choice(letters) for i in range(length))
  
output:     letters = string.ascii_lowercase
      return ''.join(random.choice(letters) for i in range(length))