title: Modify query parameters in current GET request for new url
body: <p>I access a page with the path <code>/mypage?a=1&amp;b=1&amp;c=1</code>.  I want to create a link to a similar url, with some parameters changed: <code>/mypage?a=1&amp;b=2&amp;c=1</code>, b changed from 1 to 2.  I know how to get the current arguments with <code>request.args</code>, but the structure is immutable, so I don't know how to edit them.  How do I make a new link in the Jinja template with the modified query?</p>