def random_string(length, source=string.ascii_letters + string.digits):
return '<STR_LIT>'.join(random.choice(source) for _ in range(length))<EOL>
Return random string of characters from source of specified length

    Args:
        length (int): Length of the returned string
        source (str): String of characters to use as options for randomly selected characters. Defaults to alphanumeric

    Returns:
        str: String of length number of characters composed of source characters