public function testIsLastVersion()
 {
     $o = new \VersionableBehaviorTest1();
     $this->assertTrue($o->isLastVersion());
     $o->setBar(123);
     // version 1
     $o->save();
     $this->assertTrue($o->isLastVersion());
     $o->setBar(456);
     // version 2
     $o->save();
     $this->assertTrue($o->isLastVersion());
     $o->toVersion(1);
     $this->assertFalse($o->isLastVersion());
     $o->save();
     $this->assertTrue($o->isLastVersion());
 }