ipSubnet
ipSubnet(str: String) : IpSubnet
Returns a subnet from a string, such as ipSubnet("1.2.3.4/24").
ipSubnet(ipAddr: Ipv4Address, prefixLength: Number): IpSubnet
Returns a subnet from an IP address and length, such as ipSubnet(ipAddress("1.2.3.4"), 24).
ipSubnet(ipAddr: Ipv4Address, netMask: Ipv4Address): IpSubnet
Returns a subnet from an IP address and a net mask represented as an IP address,
such as ipSubnet(ipAddress("1.2.3.4"), ipAddress("255.255.128.0")),
which is equivalent to ipSubnet("1.2.3.4/17").
This function will raise an error if the net mask parameter (second parameter) is not a valid subnet mask
(an IP address that consists of some number of leading 1 bits followed by all 0 bits).