Random article text.

    Example::

        >>> rand_article()
        ...

def rand_article(num_p=(4, 10), num_s=(2, 15), num_w=(5, 40)):
    """Random article text.

    Example::

        >>> rand_article()
        ...
    """
    article = list()
    for _ in range(random.randint(*num_p)):
        p = list()
        for _ in range(random.randint(*num_s)):
            s = list()
            for _ in range(random.randint(*num_w)):
                s.append(
                    rand_str(random.randint(1, 15), string.ascii_lowercase))
            p.append(" ".join(s))
        article.append(". ".join(p))
    return "\n\n".join(article)