public function getUser($id = null) : ?Authenticatable
    {
        if ($id === null) {
            return $this->getModel();
        }

        if (is_int($id)) {
            return $this->getById($id);
        }

        if (filter_var($id, FILTER_VALIDATE_EMAIL) !== false) {
            return $this->getByEmail($id);
        }

        return $this->getModel();
    }