keras/src/ops/nn.py/SeparableConv/compute_output_spec
class SeparableConv:    def compute_output_spec(self, inputs, depthwise_kernel, pointwise_kernel):
        output_shape = list(
            depthwise_conv(
                inputs,
                depthwise_kernel,
                self.strides,
                self.padding,
                self.data_format,
                self.dilation_rate,
            ).shape
        )
        if self.data_format == "channels_last":
            output_shape[-1] = pointwise_kernel.shape[-1]
        else:
            output_shape[1] = pointwise_kernel.shape[-1]
        return KerasTensor(output_shape, dtype=inputs.dtype)