libclass-virtual-perl 0.08-3 (s390x binary) in ubuntu kinetic

 Class::Virtual is a base class for implementing virtual base classes (what
 some people call an abstract class). Kinda kooky. It allows you to explicitly
 declare what methods are virtual and that must be implemented by subclasses.
 This might seem silly, since your program will halt and catch fire when an
 unimplemented virtual method is hit anyway, but there's some benefits.
 .
 The error message is more informative. Instead of the usual "Can't locate
 object method" error, you'll get one explaining that a virtual method was
 left unimplemented.
 .
 Subclass authors can explicitly check to make sure they've implemented all
 the necessary virtual methods. When used as part of a regression test, it
 will shield against the virtual method requirements changing out from under
 the subclass.