sub does {
    my ($proto, @methods) = @_;
    return if ref $proto && ! blessed $proto;     
    my @does;
    foreach my $method (@methods) {
        push @does, $proto->can($method) || ();
    }
    @does = () unless @does == @methods;
    return wantarray ? @does 
         : @does     ? \@does 
         :             ();
}