-spec is_bogon(binary() | string()) -> boolean().

Whether an address is private, loopback, link-local, documentation, multicast or otherwise not routable on the public internet, including the IPv6 equivalents and the 6to4 and Teredo ranges that wrap them.

Anything that is not a well-formed address is false: the API decides what counts as an address, and answering true here would swallow the 400 that tells the caller their input was wrong.