Return the x, y coordinate pairs that define the corners

def corners(self):
        """
        Return the x, y coordinate pairs that define the corners
        """

        corners = [(-self.width/2, -self.height/2),
                   ( self.width/2, -self.height/2),
                   ( self.width/2,  self.height/2),
                   (-self.width/2,  self.height/2),
                  ]
        rotmat = [[np.cos(self.angle), np.sin(self.angle)],
                  [-np.sin(self.angle), np.cos(self.angle)]]

        return np.dot(corners, rotmat) + np.array([self.center.x,
                                                   self.center.y])