def _convert_netmask(mask):
    """Convert netmask from CIDR format(integer) to doted decimal string."""
    if mask not in range(0, 33):
        raise scci.SCCIInvalidInputError(
            'Netmask value is invalid.')

    return socket.inet_ntoa(struct.pack(
        '!L', int('1' * mask + '0' * (32 - mask), 2)))
Convert netmask from CIDR format(integer) to doted decimal string.