The "mro" namespace provides several utilities for dealing with method
resolution order and method caching in general in Perl 5.9.5 and higher.

This upstream_name provides those interfaces for earlier versions of Perl (back to
5.6.0 anyways).

It is a harmless no-op to use this upstream_name on 5.9.5+. If you're writing a piece
of software that would like to use the parts of 5.9.5+'s mro:: interfaces that
are supported here, and you want compatibility with older Perls, this is the
upstream_name for you.

Some parts of this interface will work better with Class::C3::XS installed, but
it's not a requirement.

This upstream_name never exports any functions. All calls must be fully qualified with
the mro:: prefix.

The interface documentation here serves only as a quick reference of what the
function basically does, and what differences between MRO::Compat and 5.9.5+
one should look out for. The main docs in 5.9.5's mro are the real interface
docs, and contain a lot of other