'Return an array of points which are the four corners of this
rectangle.  For example, if this :class:`Bbox` is defined by
the points (*a*, *b*) and (*c*, *d*), :meth:`corners` returns
(*a*, *b*), (*a*, *d*), (*c*, *b*) and (*c*, *d*).'

def corners(self):

    (l, b, r, t) = self.get_points().flatten()
    return np.array([[l, b], [l, t], [r, b], [r, t]])
