human
Solve the following python programming problem given the following code:
def basic_auth(auth_func, after_login_func = (lambda * args, **kwargs : None), realm = 'Restricted') : 
    '
    The Basic Auth decorator for Tornado handlers.

    :param auth_fun: The function to be used for checking the credentials
    :param after_login_func: Function to run after a user successfully logs in
    :param realm: The realm to which the user is authenticating
    ' 
    def basic_auth_decorator(handler_class) : 
        '
        The template for the decorated handler class.

        :param handler_class: The Tornado handler class to be decorated.
        ' 
        def wrap_execute(handler_execute) : 
            "
            Return the handler _execute method wrapped with auth utility.

            :param handler_execute: The handler's ._execute method.
            " 
            def require_basic_auth(handler, kwargs) : 
                '
                Authenticates the user credentials.

                :param handler: The Tornado handler
                :param kwargs: Keyword arguments sent to _execute
                ' 
                def create_auth_header() : 
                    ' Create HTTP header to ask for credentials. ' 
                    handler.set_status (401) 
                    handler.set_header ('WWW-Authenticate', 'Basic realm={}'.format (realm)) 
                    handler._transforms = [] 
                    handler.finish () 
auth_header = handler.request.headers.get ('Authorization') 
                if ((auth_header is None) or (not auth_header.startswith ('Basic '))) : 
                    create_auth_header () 
                    return 
auth_decoded = base64.decodestring (auth_header [6 :]) 
                (user, pwd) = auth_decoded.split (':', 2) 
                if auth_func (user, pwd) : 
                    after_login_func (handler, kwargs, user, pwd) 
else : 
                    create_auth_header () 
def _execute(self, transforms, * args, **kwargs) : 
                '
                Wrapped Tornado handler _execute method.
               ...

    
    

    Fix the buggy line: return auth_func
assistant
#Here is Python program to fix the buggy line: return auth_func
.

return def basic_auth_decorator(