docs: def random_string(length, charset):
      """
      Return a random string of the given length from the
      given character set.
  
      :param int length: The length of string to return
      :param str charset: A string of characters to choose from
      :returns: A random string
      :rtype: str
      """
      n = len(charset)
      return ''.join(charset[random.randrange(n)] for _ in range(length))