use Test::More *;

sub f0 {
    is($_.tora(), [].tora());
}

sub f1 {
    is($_.tora(), [4].tora());
}

sub f3 {
    is($_.tora(), [1,2,3].tora());
}

f0();
f1(4);
f3(1,2,3);

done_testing();