public function getErrorReport()
    {
        if (empty($this->errors)) {
            return '';
        }
        $r = "Some arguments did not pass validation:\n";
        foreach ($this->errors as $letter => $arr) {
            $r .= "  $letter : " . implode(', ', $arr) . "\n";
        }
        $r .= "\n";

        return $r;
    }