libref-util-xs-perl 0.116-1 (amd64 binary) in ubuntu cosmic

 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.
 .
 You should use Ref::Util::XS by installing Ref::Util itself (packaged as
 libref-util-perl): If the system doesn't have Recommends turned off, you will
 get libref-util-xs-perl automatically. Ref::Util::XS will be used
 automatically, providing a significant speed boost to everything that uses
 Ref::Util.
 .
 See Ref::Util for full documentation of the available functions.