input: def generate_random_string(length: int) -> str:
      """ Generate a random string of a specified length.
      >>> generate_random_string(10)
      'aB3dF7hJk9'
      >>> generate_random_string(15)
      'Z5xW8qL2mN0pT4'
      """
      import random
      characters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
      return ''.join(random.choices(characters, k=length))
output:     import random
      characters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
      return ''.join(random.choices(characters, k=length))