4.87. kink/socket/PROTOCOL_FAMILY

Provides the enum group of the protocol families of socket API.

4.87.1. type protocol_family

`protocol_family` values are `ipv4`, `ipv6`, or `unix`.

`protocol_family` values can be compared by `op_eq` method each other.

4.87.2. PROTOCOL_FAMILY.ipv4

`ipv4` represents IPv4 protocol.

4.87.3. PROTOCOL_FAMILY.ipv6

`ipv6` represents IPv6 protocol.

4.87.4. PROTOCOL_FAMILY.unix

`unix` represents unix domain socket protocol.

4.87.5. PROTOCOL_FAMILY.is?(Val)

`is?` returns whether `Val` is a `protocol_family` value.