* Add support for /31 and /32 subnets
/31 subnets are defined by RFC 3021 and are intended for point-to-point links;
they do not reserve an IP for the network number or the broadcast address.
/32 subnets are loopback IPs.
* Correct "Useable" typo
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Co-authored-by: Caesar Kabalan <caesar.kabalan@gmail.com>