This is really a test to check out support for this change. If a Perl 6
implementation is using a Test.pm that is not supporting isa-ok, then this
will cause a lot of breakage. OTOH, it *is* dogfooding, so I think it is
I think these properties should be uncontroversial. They already hold for the current
Rakudo implementation. The basic idea is that min/max should be associative,
no matter how you group your data.