def magnitude(self, allow3d=True):
ret = self.x**<NUM_LIT:2> + self.y**<NUM_LIT:2><EOL>if allow3d: ret += self.z**<NUM_LIT:2><EOL>return ret**<NUM_LIT:0.5> <EOL>
determine the magnitude of this location from the origin (presume values represent a Vector)