title: BeautifulSoup: find all tags with a certain attribute, not value
body: <p>I want to download a file from a website using BeautifulSoup. In order to retrieve the URL, I need to access an <code>a</code> tag with a <code>download</code> attribute. I know I can filter tags by attribute by passing a <code>dict</code> to <code>BeautifulSoup.find</code> or <code>BeautifulSoup.find_all</code>, but I don't know how to deal with attributes that do not hold a value. How can I do that?</p>