<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_touch_move(self, touch):
 """If I'm being dragged, move to follow the touch."""

        if touch.grab_current is not self:
            return False
        self.center = touch.pos
        return True