class Foo {
        our $version = 0x01;
        has num32 $.bar = 1.0e0;
    }
    class Foo {
        our $version = 0x02;
        has uint32 $.bar = 0xFF_FF_FF_FF; # changed type
        has uint8 $.baz = 0xAA; # added new attribute
    }
    my $ty = Foo; say $ty.WHO{'$version'};
    say Foo.^attributes;