$xml->save($filename) or die "Couldn't save my xml data to $filename: $!";

##</code><code>##

# ... near the top:
use Carp;  # THIS NEEDS TO BE ADDED
# ...

sub save {
    my $this = shift ;
    my $file = shift ;

    if (-d $file || (-e $file && !-w $file)) {
# NEED TO ADD THE "carp" CALL:
        carp "Unusable file name passed to XML::Smart->save ($file is a directory or read-only file)\n";
        return ;
    }

    my ($data,$unicode) = $this->data(@_) ;
 
    my $fh;
    open( $fh, ">$file" ) or return;
    binmode( $fh ) if $unicode;
    print $fh $data or return;
    close $fh;   # save() will return true if this succeeds, false otherwise
}