def kvnr(self) -> str:
        """
        German health insurance number ("Krankenversichertennummer", abbr. "KVNR")

        Source: https://de.wikipedia.org/wiki/Krankenversichertennummer

        :return: a random health insurance number
        """

        letter_number: str = str(self.random_int(min=1, max=26))
        if len(letter_number) == 1:
            letter_number = "0" + letter_number

        first_part_format: str = letter_number + "########"
        first_part: str = self.numerify(first_part_format)
        first_checkdigit: int = luhn_checksum(int(first_part[::-1]))
        second_part_format: str = "#########"
        second_part: str = self.numerify(second_part_format)

        kvnr: str = first_part + str(first_checkdigit) + second_part
        kvnr_checkdigit: int = luhn_checksum(int(kvnr[::-1]))
        kvnr = kvnr + str(kvnr_checkdigit)

        letter: str = ascii_uppercase[int(letter_number) - 1]
        kvnr = letter + kvnr[2:]

        return kvnr

        German health insurance number ("Krankenversichertennummer", abbr. "KVNR")

        Source: https://de.wikipedia.org/wiki/Krankenversichertennummer

        :return: a random health insurance number
        
faker/providers/ssn/de_DE/__init__.py