Module::Implementation 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.
 .
 This module is only useful when you know all the implementations ahead of
 time. If you want to load arbitrary implementations then you probably want
 something like a plugin system, not this module.