<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def on_destination(self, *args):
 """Make sure to redraw whenever the destination moves."""

        if self.destination is None:
            Clock.schedule_once(self.on_destination, 0)
            return
        self.destination.bind(
            pos=self._trigger_repoint,
            size=self._trigger_repoint
        )