我有下面的模式：

class Group extends Model
{
    /**
     * The users that belong to the group.
     */
    public function users()
    {
        return $this->belongsToMany(User::class)->withTimestamps();
    }
}

我的User模型在另一面应该是什么样子？

class User extends Model
{
    /**
     * The group that owns the user.
     */
    public function group()
    {
        return $this->???(Group::class)->withTimestamps();
    }
}