[L5.1] Model Factories and Relationships

I am playing withe the new Model Factory feature, but I don't know how to use relationship in it.

In my project a User has may Status(es) and a Status belongs to a User

This is my ModelFactory.php file:

$factory->define(App\User::class, function ($faker) {
    return [
        'name' => $faker->name,
        'email' => $faker->email,
        'password' => str_random(10),
        'remember_token' => str_random(10),
    ];
});

$factory->define(App\Status::class, function ($faker) {
    return [
        'body' => $faker->sentence,
        'user_id' => /* WHAT DO I WRITE HERE? */,
    ];
});

What do I write for user_id ?