push @{$default_options->{value_callbacks}}, sub {
my ($value) = @_;
# Replace "u" with "0" for sorting
return map { s/[u\s]/0/gr } ( $value =~ /[0-9u\s]{4}/g );
return map { /[0-9u]{4}/g } ( $value =~ s/u/0/gr );
};
}
-