OutputFile => <file specifier> # out - handy

       The default behaviour of "XMLout()" is to return the XML as a string.
       If you wish to write the XML to a file, simply supply the filename
       using the 'OutputFile' option.

       This option also accepts an IO handle object - especially useful in
       Perl 5.8.0 and later for writing out in an encoding other than UTF-8,
       eg:

         open my $fh, '>:encoding(iso-8859-1)', $path or die "open($path): $!";
         XMLout($ref, OutputFile => $fh);