@vecrec.accept_anything_as_vector<EOL><INDENT>def jump_percent(self, new_percent):<DEDENT>
self._require_rects()<EOL>self.jump(new_percent * self.unoccupied_size)<EOL>
new_percent should be between -1.0 and 1.0.  Values outside this range 
are not illegal, but they will be clamped into it.