public function assignRole($user, $role)
    {
        if (is_int($user) and !$user = User::where('id', $user)->first()) {
            return false;
        }
        if (is_int($role) and !$role = Roles::where('id', $role)->first()) {
            return false;
        }
        if (is_string($role) and !$role = Roles::where('name', $role)->first()) {
            return false;
        }
        if (!($user instanceof User) or !($role instanceof Roles)) {
            return false;
        }
        return $role->assignToUser($user);
    }