function based wsgi container and return value bytes expected

In going through the docs, i saw a snippet to test a wsgi container, and ran as-is in a fresh environment. What i encountered was an error related to the docs such that the return value did not encode to bytes to send as the output of the WSGI container rudimentary function. Specifically, in https://www.tornadoweb.org/en/stable/wsgi.html

import tornado
import tornado.wsgi
import tornado.httpserver
import tornado.ioloop

def simple_app(environ, start_response):
    status = "200 OK"
    response_headers = [("Content-type", "text/plain")]
    start_response(status, response_headers)
    return ["Hello world!\n"]

container = tornado.wsgi.WSGIContainer(simple_app)
http_server = tornado.httpserver.HTTPServer(container)
http_server.listen(8888)
tornado.ioloop.IOLoop.current().start()

The fix i applied was to change

return ["Hello world!\n"]

into

return ["Hello world!\n".encode("utf-8")]

Would a docs update suffice to contain this? Worth putting in a doc test? I would be a first time contributor here for the PR if so.

Thanks!

Start with the WSGI example at the documentation URL named in the issue and verify its return value against the WSGI bytes requirement. Done means the published example runs successfully in a fresh environment; the payload does not name a documentation file or test entry point.