NUMBERS_PLUS_LETTER = "Input must be a string of 8 numbers plus letter" LOOKUP_LETTERS = "TRWAGMYFPDXBNJZSQVHLCKE" def is_spain_national_id(spanish_id: str) -> bool: """ Spain National Id is a string composed by 8 numbers plus a letter The letter in fact is not part of the ID, it acts as a validator, checking you didn't do a mistake when entering it on a system or are giving a fake one. https://en.wikipedia.org/wiki/Documento_Nacional_de_Identidad_(Spain)#Number >>> is_spain_national_id("12345678Z") True >>> is_spain_national_id("12345678z") # It is case-insensitive True >>> is_spain_national_id("12345678x") False >>> is_spain_national_id("12345678I") False >>> is_spain_national_id("12345678-Z") # Some systems add a dash True >>> is_spain_national_id("12345678") Traceback (most recent call last): ... ValueError: Input must be a string of 8 numbers plus letter >>> is_spain_national_id("123456709") Traceback (most recent call last): ... ValueError: Input must be a string of 8 numbers plus letter >>> is_spain_national_id("1234567--Z") Traceback (most recent call last): ... ValueError: Input must be a string of 8 numbers plus letter >>> is_spain_national_id("1234Z") Traceback (most recent call last): ... ValueError: Input must be a string of 8 numbers plus letter >>> is_spain_national_id("1234ZzZZ") Traceback (most recent call last): ... ValueError: Input must be a string of 8 numbers plus letter >>> is_spain_national_id(12345678) Traceback (most recent call last): ... TypeError: Expected string as input, found int """ if not isinstance(spanish_id, str): raise TypeError(f"Expected string as input, found {type(spanish_id).__name__}") spanish_id_clean = spanish_id.replace("-", "").upper() if len(spanish_id_clean) != 9: raise ValueError(NUMBERS_PLUS_LETTER) try: number = int(spanish_id_clean[0:8]) letter = spanish_id_clean[8] except ValueError as ex: raise ValueError(NUMBERS_PLUS_LETTER) from ex if letter.isdigit(): raise ValueError(NUMBERS_PLUS_LETTER) return letter == LOOKUP_LETTERS[number % 23] if __name__ == "__main__": import doctest doctest.testmod()