If user provide an empty string as network range, inet_pton will
treate it as an IPv6 unspecified address, it seems a bug but I
can't confirm. Then empty string will be converted to 0, 0 & 1
always be zero, so it caused dead loop.
Usage:
Use IPNetwork(str|list<str>) to create an IPNetwork object.
Use operator 'in' to determine whether the specified
IP address is in the IP network or not, like:
>>> '192.168.1.1' in IPNetwork('192.168.1.0/24')
True
Both IPv4 and IPv6 address are supported.
Note: When using string to initialize the IPNetwork,
a comma seperated IP network list should be provided.
Currently, IPNetwork just support standard CIDR like:
x.x.x.x/y eg. 192.168.1.0/24
::x/y eg. ::1/10
If pure IP address was provided,
it will be treated as implicit IP network,
like 192.168.0.0 will be treated as 192.168.0.0/16
and 192.168.1.1 will be treated as 192.168.1.1/32
This implicit translate may cause some unexpected behavior,
like user provide 192.168.2.0 and expect it will be treated as
192.168.2.0/24 but actually it will be translated to
192.168.2.0/23 because there are 9 continuous 0 from right.
In order to avoid confusion, a warning message
will be displayed when pure IP address was provided.
Other variants of CIDR are not supported yet.
