def _find_one_after_last_labeled_index(self):
        body_index = 0
        while self.bodies[body_index].segment_id in self.state.body_labels:
            body_index += 1
        return body_index
def test_critical_angle():
    m1 = Medium('m1', n=1)
    m2 = Medium('m2', n=1.33)
    assert ae(critical_angle(m2, m1), 0.85, 2)