private function prepareContent($data)
    {
        $content = '';

        foreach ($data as $row) {
            $content .= $this->convertToJson($row) . static::ROW_DELIMITER;
        }

        return $content;
    }
private function prepareContent($data)
    {
        $content = '';

        foreach ($data as $row) {
            $content .= $this->convertToJson($row) . static::ROW_DELIMITER;
        }

        return $content;
    }
private function prepareContent ( $ data ) { $ content = '' ; foreach ( $ data as $ row ) { $ content .= $ this -> convertToJson ( $ row ) . static :: ROW_DELIMITER ; } return $ content ; }
Prepare content string from given data

@param \Traversable|array $data

@return string
Prepare content string from given data