human
Solve the following python programming problem given the following code:
def authenticator(session_manager, login_url = '/auth/login') : 
    "Create an authenticator decorator.

    :param session_manager: A session manager class to be used for storing
            and retrieving session data.  Probably based on
            :class:`BaseSession`.
    :param login_url: The URL to redirect to if a login is required.
            (default: ``'/auth/login'``).
    " 
    def valid_user(login_url = login_url) : 
        def decorator(handler, * a, **ka) : 
            import functools 
            @ functools.wraps (handler) 
            def check_auth(* a, **ka) : 
                try : 
                    data = session_manager.get_session () 
                    if (not data ['valid']) : 
                        raise KeyError ('Invalid login') 
except (KeyError, TypeError) : 
                    bottle.response.set_cookie ('validuserloginredirect', bottle.request.fullpath, path = '/', expires = (int (time.time ()) + 3600)) 
                    bottle.redirect (login_url) 
if data.get ('name') : 
                    bottle.request.environ ['REMOTE_USER'] = data ['name'] 
return handler (* a, ** ka) 
return check_auth 
return decorator 
return login_url 

    
    

    Fix the buggy line: return login_url
assistant
#Here is Python code to fix the buggy line: return login_url
.

return def valid_user(