def get_product_description(soup):
    """ Analyze "soup" to extract product's description.

    Args:
      soup -- bs4.BeautifulSoup from http request of book url.
    Return:
        product's description
    """
    article = soup.find("article", "product_page")
    product_description = article.find_all("p")[3].text

    return str(product_description)