// Example 1.
final $data = true;

if (is_final($data)) {
    // It doesn't make sense, because I know that $data is final.
}

// Example 2.
class AnotherPackageClass {
    final public $data;
}

$reflection = new ReflectionProperty(AnotherPackageClass::class, 'data');
echo $reflection->isFinal(); // true