keras/src/ops/numpy.py/Ravel/compute_output_spec
class Ravel:    def compute_output_spec(self, x):
        if None in x.shape:
            output_shape = [
                None,
            ]
        else:
            output_shape = [int(np.prod(x.shape))]
        return KerasTensor(output_shape, dtype=x.dtype)