my @libxml_args;
if (OFFLINE) {
    @libxml_args = ([IO => \*DATA]);
} else {
    @libxml_args = map { [location => $_] } $io->all(0);
}
for my $libxml_arg (@libxml_args) {
    my $dom = 'XML::LibXML'->load_xml(@$libxml_arg);
    ...
}