def _get_surname_letters(self) -> str:
        """
            Rules:
            * if consonants >=3 : take the first 3
            * if less, pad them with vowels; vowels come after the consonants and in the order they appear (ROSA -> RSO)
            * if surname is less than 3 chars, pad it on the right with 'X'  (FO -> FOX)
        Returns:
            str
        """
        surname = self.generator.last_name().upper()
        surname = self._transliterate_name(surname)

        if len(surname) < 3:
            return self._pad_shorter(surname)

        surname_consonants = self._get_consonants(surname)
        cons_len = len(surname_consonants)

        if cons_len < 3:
            surname_part = "".join(surname_consonants + self._get_vowels(surname))[:3]
        else:
            surname_part = "".join(surname_consonants)[:3]
        return surname_part

            Rules:
            * if consonants >=3 : take the first 3
            * if less, pad them with vowels; vowels come after the consonants and in the order they appear (ROSA -> RSO)
            * if surname is less than 3 chars, pad it on the right with 'X'  (FO -> FOX)
        Returns:
            str
        
faker/providers/ssn/it_IT/__init__.py