public function prepare($sql, string $stmt = 'stmt'): Database
    {
        $stmt = 'prepare_' . $stmt;
        try {
            $this->$stmt = $this->connection->prepare($sql);
        } catch (PDOException $e) {
            throw new CoreException(
                __CLASS__.'::prepare()->PDO::prepare() : ' . $e->getMessage()
            );
        }
        $store_sql        = $stmt . '_sql';
        $this->$store_sql = $sql;

        return $this;
    }