Traceback (most recent call last):
  File "/workspace/Paddle/test.py", line 65, in <module>
    out = layer(img)
  File "/workspace/Paddle/build/python/paddle/nn/layer/layers.py", line 1532, in __call__
    return self.forward(*inputs, **kwargs)
  File "/workspace/Paddle/build/python/paddle/jit/dy2static/program_translator.py", line 535, in __call__
    return self._perform_call(*args, **kwargs)
  File "/workspace/Paddle/build/python/paddle/jit/dy2static/program_translator.py", line 863, in _perform_call
    error_data.raise_new_exception()
  File "/workspace/Paddle/build/python/paddle/jit/dy2static/error.py", line 454, in raise_new_exception
    raise new_exception from None
AttributeError: In transformed code:
    File "/workspace/Paddle/test.py", line 31, in forward
        out = DemoPyLayer.apply(x)
    File "/workspace/Paddle/test.py", line 11, in forward
        @staticmethod
        def forward(ctx, x):
            ctx.x = x
            ~~~~~~~~~ <--- HERE
            # ctx.save_for_backward(x)
            x1 = paddle.tanh(x)
    File "/workspace/Paddle/build/python/paddle/jit/dy2static/py_layer.py", line 43, in __setattr__
        raise AttributeError(
    AttributeError: `ctx.x = tensor` is not allowed in static mode, please use `ctx.save_for_backward(tensor)` instead.
For example:
    >>> class ExamplePyLayer(PyLayer):
    ...     @staticmethod
    ...     def forward(ctx, x):
    ...         # ctx.x = x  # This is not allowed in static mode, Replace it with `ctx.save_for_backward(x)`
    ...         ctx.save_for_backward(x)
    ...         x1 = paddle.tanh(x)
    ...         return x1
    ...     @staticmethod
    ...     def backward(ctx, grad):
    ...         # x = ctx.x  # Same as above, replace it with `x, = ctx.saved_tensor()`
    ...         x, = ctx.saved_tensor()
    ...         x_grad = grad * (1 - paddle.square(x))
    ...         return x_grad