Internal Program Version: Module::Implementation  0.90.0.5.42.0

This module abstracts out the process of choosing one of 
several underlying implementations for a module. This can 
be used to provide XS and pure Perl implementations of a 
module, or it could be used to load an implementation
for a given OS or any other case of needing to provide multiple
implementations.

http://search.cpan.org/dist/Module-Implementation