private function _store_user( $store = true ) {
            $this->_logger->entrance();

            if ( empty( $this->_user->id ) ) {
                $this->_logger->error( "Empty user ID, can't store user." );

                return;
            }

            $users                     = self::get_all_users();
            $users[ $this->_user->id ] = $this->_user;
            self::$_accounts->set_option( 'users', $users, $store );
        }