pragma for using the C3 method resolution order

 Class::C3 is a Perl pragma that modifies the standard method resolution order
 from depth-first left-to-right to the more sophisticated C3 method resolution
 order.
 .
 The C3 algorithm aims to provide a sane method resolution order with multiple
 inheritance. It was first introduced in the Dylan language, later adopted for
 Python 2.3. It is also the canonical MRO implementation for Perl 6 classes
 and is the default for Parrot objects as well.