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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def authenticated( """Decorate methods with this to require that the user be logged in. If the user is not logged in, they will be redirected to the configured `login url <RequestHandler.get_login_url>`. If you configure a login url with a query parameter, Tornado will assume you know what you're doing and use it as-is. If not, it will add a `next` parameter so the login page knows where to send you once you're logged in. """


    @functools.wraps(method)
    def wrapper(  # type: ignore
        self: RequestHandler, *args, **kwargs
    ) -> Optional[Awaitable[None]]:
        if not self.current_user:
            if self.request.method in ("GET", "HEAD"):
                url = self.get_login_url()
                if "?" not in url:
                    if urllib.parse.urlsplit(url).scheme:
                        # if login url is absolute, make next absolute too
                        next_url = self.request.full_url()
                    else:
                        assert self.request.uri is not None
                        next_url = self.request.uri
                    url += "?" + urlencode(dict(next=next_url))
                self.redirect(url)
                return None
            raise HTTPError(403)
        return method(self, *args, **kwargs)

    return wrapper