Often there are several possible providers of some functionality your
program needs, but you don't know which is available at the run site.
For example, one of the modules may be implemented with XS, or not in
the core Perl distribution and thus not necessarily installed.

Best.pm attempts to load modules from a list, stopping at the first
successful load and failing only if no alternative was found.

WWW: https://metacpan.org/release/Best