human
I wrote the below code

    def ellipsoid(x, y, z, x0=13, y0=10, z0=8, a=4, b=3, c=2, amp=1):
        rsq = (((((x - x0) / a) ** 2) + (((y - y0) / b) ** 2)) + (((z - z0) / c) ** 2))
        val = ((rsq < 1) * amp)
        return val
    class Ellipsoid3D(models.custom_model(ellipsoid), ):
        @property
        def bounding_box(self):
            return (((self.z0 - self.c), (self.z0 + self.c)), ((self.y0 - self.b), (self.y0 + self.b)), ((self.x0 - self.a), (self.x0 + self.a)))
    model = Ellipsoid3D()
    bbox = model.bounding_box
    (zlim, ylim, xlim) = bbox
    (dz, dy, dx) = (np.diff(bbox) / 2)
    (z1, y1, x1) = np.mgrid[(slice(zlim[0], (zlim[1] + 1)), slice(ylim[0], (ylim[1] + 1)), slice(xlim[0], (xlim[1] + 1)))]
    (z2, y2, x2) = np.mgrid[(slice((zlim[0] - dz), ((zlim[1] + dz) + 1)), slice((ylim[0] - dy), ((ylim[1] + dy) + 1)), slice((xlim[0] - dx), ((xlim[1] + dx) + 1)))]
    arr = model(x2, y2, z2)
    sub_arr = model(x1, y1, z1)
    assert (abs((arr.sum() - sub_arr.sum())) < (arr.sum() * 1e-07))

What's a good function header?
 ... Here's a good function header?
assistant
#Here's a good function header.

def test_custom_model_bounding_box():