human
Solve the following python programming problem given the following code:
@ defer.inlineCallbacks 
def do_task(self, task) : 
    'Return the result of the task or raise a TaskFailed exception on failure.' 
    rtn = defer.Deferred () 
    def _on_fail() : 
        rtn.errback (self.TaskFailed ('Task failed')) 
task.on_fail.append (_on_fail) 
    task.on_complete.append (rtn.callback) 
    taskset = Taskset ([task]) 
    taskset.handles = { 
        
} 
    c = self._submit_task (task) 
    taskset.connections = set ([c]) 
    def _do_cmd(* args) : 
        return self._command_handler (taskset, c, * args) 
with _ConnectionWrapper (c, _do_cmd) : 
        rtn = (yield rtn) 
defer.returnValue (_on_fail) 

    
    

    Fix the buggy line: defer.returnValue (_on_fail)
assistant
#Here is Python code to fix the buggy line: defer.

defer.returnValue (rtn)