sub sheetNames {
    my $xlsx = shift;
    my %ret;
    my $sheet = $xlsx->getFirstSheet;
    while ($sheet) {
        $ret{$xlsx->currentSheetName} = $xlsx->currentSheetNum;
        $sheet = $xlsx->getNextSheet;
    }
    return %ret;
}

sub selectSheet {
    my ($xlsx,$name) = @_;
    my %available = sheetNames $xlsx;
    $xlsx->setCurrentSheetNum($available{$name});
}

##</code><code>##

selectSheet $ss2, 'My Great Sheet';