django减去两次以恢复静止时间

Question

您好，当我尝试减去两个datetime.time时，我得到了错误 错误是：

unsupported operand type(s) for -: 'datetime.time' and 'datetime.time'

我的views.py是：

if(allreservertion.heuredebut==        form.cleaned_data['heuredebut']):

      x=   dt.datetime.strftime(form.cleaned_data['heuredebut'] - 
      form.cleaned_data['heurefin'])
      y= dt.datetime.time(allreservertion.heuredebut+             
      allreservertion.heurefin)
      print(x)
      print(y)
      print("meme heure début")
      return render(request,'registration/plan.html')