def gaussian_pyramid(self, n_levels=3, downscale=2, sigma=None):
        r"""
        Return the gaussian pyramid of this image. The first image of the
        pyramid will be the original, unmodified, image, and counts as level 1.

        Parameters
        ----------
        n_levels : `int`, optional
            Total number of levels in the pyramid, including the original
            unmodified image
        downscale : `float`, optional
            Downscale factor.
        sigma : `float`, optional
            Sigma for gaussian filter. Default is ``downscale / 3.`` which
            corresponds to a filter mask twice the size of the scale factor
            that covers more than 99% of the gaussian distribution.

        Yields
        ------
        image_pyramid: `generator`
            Generator yielding pyramid layers as :map:`Image` objects.
        """
        from menpo.feature import gaussian_filter
        if sigma is None:
            sigma = 3. / downscale
        image = self
        yield image
        for level in range(n_levels - 1):
            image = gaussian_filter(image, sigma).rescale(1.0 / downscale)
            yield image
dataset/ETHPy150Open menpo/menpo/menpo/image/base.py/Image.gaussian_pyramid/swapped operands of `/`