From https.pm:

use base qw(Net::HTTPS LWP::Protocol::http::SocketMethods);

This tells us that it uses those as "base" classses, inheriting methods from them.

In HTTPS.pm from the Net::HTTPS package it runs through some hoops to decide an appropriate socket class $SSL_SOCKET_CLASS, and then has:

our @ISA=($SSL_SOCKET_CLASS, 'Net::HTTP::Methods');

which is another way of achieving something similar to use base.

The choices for the $SSL_SOCKET_CLASS are IO::Socket::SSL or Net::SSL, so you need to have at least one of those installed for it to work (and provide a new() function).

Does that help you get any further?