What’s new in Tornado 4.5.1 What’s new in Tornado 4.5.1 Apr 20, 2017 tornado.log tornado.httputil What’s new in Tornado 4.5.1 What’s new in Tornado 4.5.1 Apr 20, 2017 tornado.log Improved detection of libraries for colorized logging. tornado.httputil url_concat once again treats None as equivalent to an empty sequence.