sub unuriescape
{
    # Note from RFC1630:  "Sequences which start with a percent sign
    # but are not followed by two hexadecimal characters are reserved
    # for future extension"
    my $str = shift;
    if (@_ && wantarray) {
        # not executed for the common case of a single argument
        my @str = @_;  # need to copy
        return map { s/%([0-9A-Fa-f]{2})/chr(hex($1))/eg } $str, @str;
    }
    $str =~ s/%([0-9A-Fa-f]{2})/chr(hex($1))/eg;
    $str;
}