Subnet IP range calculation.
We may need to known the IP range of a subnet in our program sometimes. The subnet may like 172.16.1.19/20, and the IP shoud range from 172.16.1.19 to 172.16.15.255. To conveniently invoke function, I try to write a package to provide calculation of subnet IP range.
You can test this package by range_test.go like following:
go test range_test.go