input: 
  from typing import List
  import random
  import string
  
  def generate_random_string(length: int) -> str:
      """
      Generate a random string of specified length consisting of lowercase letters.
      >>> generate_random_string(6)
      'abcdef'
      >>> generate_random_string(6)
      'zyxwvu'
      """
      letters = string.ascii_lowercase
      return ''.join(random.choice(letters) for _ in range(length))
  
output:     return ''.join(random.choice(string.ascii_lowercase) for _ in range(length))