title: schedule_task() argument after * must be an iterable, not int
body: <p>Here I am using <code>apply_async</code> method with <code>countdown</code> and <code>expires</code> arguments to execute the task after some countdown and expires the task at certain datetime.</p>
  
  <p>But I got this error </p>
  
  <pre><code>Django Version: 3.0.6 
  Exception Type: TypeError
   Exception Value:    schedule_task() argument after * must be an iterable, not int
  </code></pre>
  
  <p>How to solve this error ? </p>
  
  <p>tasks</p>
  
  <pre><code>@periodic_task(run_every=crontab(minute=1), ignore_result=False)  
  def schedule_task(pk):
  
      task = Task.objects.get(pk=pk)
      unique_id = str(uuid4()) 
  </code></pre>
  
  <p>views</p>
  
  <pre><code>form = CreateTaskForm(request.POST)
          if form.is_valid():
  
              unique_id = str(uuid4())
              obj = form.save(commit=False)           
              obj.created_by = request.user
              obj.unique_id = unique_id
              obj.status = 0
              obj.save()
              form.save_m2m()
              # schedule_task.delay(obj.pk)
              schedule_task.apply_async((obj.pk),expires=datetime.datetime.now() + datetime.timedelta(minutes=5), countdown=int(obj.search_frequency))
  
              return redirect('crawler:task-list')
  </code></pre>