human
Solve the following python programming problem given the following code:
@ override_settings (SLACK_INTERNAL = True) 
@ override_settings (SLACK_EXPERTS = True) 
def test_notify_status_change(self) : 
    project = self.projects ['empty_project'] 
    internal_name = settings.SLACK_INTERNAL_NOTIFICATION_CHANNEL.strip ('#') 
    internal_groups = [group for group in self.slack.groups.list ().body ['groups'] if (group ['name'] == internal_name)] 
    internal_group_id = internal_groups [0] ['id'] 
    internal_slack_messages = self.slack.get_messages (internal_group_id) 
    experts_slack_messages = self.slack.get_messages (project.slack_group_id) 
    def _validate_slack_messages(message_stub) : 
        '
            Check that correct slack message was sent if API key present.
            ' 
        self.assertIn (message_stub, internal_slack_messages.pop ()) 
        self.assertIn (message_stub, experts_slack_messages.pop ()) 
task = TaskFactory (project = project, step = self.test_step, status = Task.Status.AWAITING_PROCESSING) 
    self.assertEquals (task.status, Task.Status.AWAITING_PROCESSING) 
    task = assign_task (self.workers [0].id, task.id) 
    self.assertTrue (is_worker_assigned_to_task (self.workers [0], task)) 
    self.assertEquals (len (self.mail.inbox), 1) 
    notification = self.mail.inbox.pop () 
    self.assertEquals (notification ['recipient'], self.workers [0].user.email) 
    self.assertEquals (notification ['subject'], "You've been assigned to a new task!") 
    _validate_slack_messages ('Task has been picked up by a worker.') 
    self.assertEquals (len (internal_slack_messages), 0) 
    self.assertEquals (len (experts_slack_messages), 0) 
    with patch ('orchestra.utils.task_lifecycle._is_review_needed', return_value = True) : 
        task = submit_task (task.id, { 
            
}, Iteration.Status.REQUESTED_REVIEW, self.workers [0]) 
self.assertEquals (task.status, Task.Status.PENDING_REVIEW) 
    self.assertEquals (len (self.mail.inbox), 1) 
    notification = self.mail.inbox.pop () 
    self.assertEquals (notification ['recipient'], self.workers...
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here is a proper replacement for <MASK>.
experts_slack_messages