my $zip = Archive::Zip->new( $infile );
my $content = $zip->contents('content.xml');
my $workbook_ref = read_xml_string($content);
foreach my $sheet ( sort keys %$workbook_ref ) {
  foreach my $row( @{$$workbook_ref{$sheet}} ) {
    foreach my $cell_contents (@{$row}){
      next unless defined( $cell_contents );
      $cell_contents = replace_higher_unicode_code_points($cell_contents);
etc