Under older perls this module provides a drop in compatible api to
Hash::Util::FieldHash using perltie. When Hash::Util::FieldHash is available
it will use that instead.

This way code requiring field hashes can benefit from fast, robust field
hashes on Perl 5.10 and newer, but still run on older perls that don't ship
with that module.

WWW: https://metacpan.org/release/Hash-Util-FieldHash-Compat