Ref::Util::XS is the XS implementation of Ref::Util, which provides several functions to help identify references in a more convenient way than the usual approach of examining the return value of ref.
acquired package info from repodata DB: repodata/f1f85c23079e7764ad00378a9fc5d660b89a03657290e75426caf7be5b7da462-primary.sqlite.bz2