Call to static method on an unknown class 

```php
class Foo
{
	public function bar()
	{
		if (class_exists('\Bla')) {
			Bla::baz();
		}
	}
}
```

produces `Call to static method baz() on an unknown class Bla`, if the `Bla` class really does not exist. What should we do in this case? Or, what can we do?