import ipaddress


def address_with_mask(address, mask):
    """
    check if given ip address and mask combination is valid
    :param address: string ip_address
    :param mask: int net prefix/mask
    :return: boolean
    """
    merged = u"{}/{}".format(address, mask)
    try:
        ipaddress.ip_network(merged)
    except ValueError:
        return False

    return True