'Tuple defining the default ``bounding_box`` limits.
``((y_low, y_high), (x_low, x_high))``'

@property
def bounding_box(self):

    return (((self.y_0 - self.R_0), (self.y_0 + self.R_0)), ((self.x_0 - self.R_0), (self.x_0 + self.R_0)))
