Traceback (most recent call last):
  File "D:/untitled/shouxiti.py", line 25, in <module>
    model.add(Dense(512,activation="relu",input_shape=(784,)))     #输入层
  File "D:\Anacona\envs\tensorflow\lib\site-packages\tensorflow\python\training\tracking\base.py", line 457, in _method_wrapper
    result = method(self, *args, **kwargs)
TypeError: add() missing 1 required positional argument: 'layer'