def mask(scope, ips, mask):
    """
    Applies the given IP mask (e.g. 255.255.255.0) to the given IP address
    (or list of IP addresses) and returns it.

    :type  ips: string
    :param ips: A prefix, or a list of IP prefixes.
    :type  mask: string
    :param mask: An IP mask.
    :rtype:  string
    :return: The network(s) that result(s) from applying the mask.
    """
    mask = ipv4.ip2int(mask[0])
    return [ipv4.int2ip(ipv4.ip2int(ip) & mask) for ip in ips]
Applies the given IP mask (e.g. 255.255.255.0) to the given IP address
    (or list of IP addresses) and returns it.

    :type  ips: string
    :param ips: A prefix, or a list of IP prefixes.
    :type  mask: string
    :param mask: An IP mask.
    :rtype:  string
    :return: The network(s) that result(s) from applying the mask.