def update_rect(self):
if self.vertex_list:<EOL><INDENT>self.vertex_list.vertices = (<EOL>self._rect.bottom_left.tuple +<EOL>self._rect.bottom_right.tuple +<EOL>self._rect.top_right.tuple +<EOL>self._rect.top_left.tuple<EOL>)<EOL><DEDENT>
Call this method to update the tile after you've made an in-place 
change to its rectangle.