Webmozart\Assert\Assert::alpha PHP Method

    public static function alpha($value, $message = '')
    {
        $locale = setlocale(LC_CTYPE, 0);
        setlocale(LC_CTYPE, 'C');
        $valid = !ctype_alpha($value);
        setlocale(LC_CTYPE, $locale);
        if ($valid) {
            static::reportInvalidArgument(sprintf($message ?: 'Expected a value to contain only letters. Got: %s', static::valueToString($value)));
        }
    }