input: def generate_random_string(length: int) -> str:
      """ Generate a random string of specified length containing alphanumeric characters.
      >>> generate_random_string(8)
      'aB34cD56'
      >>> generate_random_string(8)
      '7eFg8hI9'
      """
output:     
      import random
      import string
  
      return ''.join(random.choices(string.ascii_letters + string.digits, k=length))
  