sub checksum {
    my $s = shift;
    utf8::downgrade($s, 1)
        or croak("Wide character in subroutine entry");
    return unpack("%32C*", $s) % 65535;
}

##</code><code>##

sub checksum {
    my $s = shift;
    if (defined(&utf8::downgrade)) {
        utf8::downgrade($s, 1)
            or croak("Wide character in subroutine entry");
    }
    return unpack("%32C*", $s) % 65535;
}