Return a rectangle with extended borders.

        Create a new rectangle that is wider and taller than the
        immediate one. All sides are extended by "n" points.

def expanded_by(self, n):
        """Return a rectangle with extended borders.

        Create a new rectangle that is wider and taller than the
        immediate one. All sides are extended by "n" points.
        """
        return Rect(self.left - n, self.top - n, self.right + n, self.bottom + n)