input: 
  import random
  import string
  
  def random_string(length: int) -> str:
      """Generate a random string of given length composed of lowercase letters.
      
      >>> random_string(6)
      'abcdef'
      >>> random_string(6)
      'ghijkl'
      """
      letters = string.ascii_lowercase
      return ''.join(random.choice(letters) for i in range(length))
  
output:     return ''.join(random.choices(letters, k=length))