human
Solve the following python programming problem given the following code:
def login_required(f) : 
    'Redirect to login page if user not logged in' 
    @ wraps (f) 
    def decorated_function(* args, **kwargs) : 
        if (not session.get ('logged_in')) : 
            flash ('Login required', 'error') 
            return redirect (url_for ('login', next = request.url)) 
return f (* args, ** kwargs) 
return <MASK> 
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here is a proper replacement for <MASK>.
def decorated_function(