Grow this rectangle by the given padding on all sides.

def grow(self, *padding):
        """ Grow this rectangle by the given padding on all sides. """
        try:
            lpad, rpad, tpad, bpad = padding
        except ValueError:
            lpad = rpad = tpad = bpad = padding[0]

        self._bottom -= bpad
        self._left -= lpad
        self._width += lpad + rpad
        self._height += tpad + bpad
        return self