import datetime
from schwifty import IBAN, BIC


def mandatory(field: str) -> bool:
    return bool(field)


def empty(field: str) -> bool:
    return not bool(field)


def iso_date(field: str) -> bool:
    try:
        datetime.datetime.strptime(field, "%Y-%m-%d")
        return True
    except ValueError:
        return False


def valid_iban(field: str) -> bool:
    try:
        IBAN(field)
        return True
    except ValueError:
        return False


def valid_bic(field: str) -> bool:
    try:
        BIC(field)
        return True
    except ValueError:
        return False