def company_vat(self) -> str:
        """
        Returns Finnish VAT identification number (Arvonlisaveronumero).
        This can be calculated from company business identity code by
        adding prefix "FI" and removing dash before checksum.
        """

        def convert_to_vat(business_id: str) -> str:
            """
            Convert business id to VATIN
            """
            return "FI" + business_id.replace("-", "")

        return convert_to_vat(self.company_business_id())

        Returns Finnish VAT identification number (Arvonlisaveronumero).
        This can be calculated from company business identity code by
        adding prefix "FI" and removing dash before checksum.
        
faker/providers/company/fi_FI/__init__.py