if($object != null && is_object($object) && method_exists($object,'ok'))

<?
class MyClass{

public function hello(){
MyClass::world($this);
}
   
public function ok(){
echo 'ok: ok';
}

static function world($object = null){
if($object != null && is_object($object) && method_exists($object,'ok')){
$object->ok();
echo'World';
}
}


}

$test = new MyClass;
$test->hello();