Implemented callback as the action:

Now you can provide a callback as the action, which will receive
the entire result before it's sent to the user (lacking the 'action',
of course, because it wasn't determined yet), and you could then
return whatever result you want.

    my $rules = {
        CEO => {
            SecretData => [
                [ 1, { superpower => 1 } ],
                [
                    sub {
                        my $result = shift;
                        check_something()
                            and return 1;
                    },
                    'possibly_superpower',
                ]
            ],
        },
    };