undef $self->{xml};
>> C:/perl/site/5.14.1/lib/XML/Twig.pm:7534:     { my $elt= shift;
>> C:/perl/site/5.14.1/lib/XML/Twig.pm:7535:       return if( $XML::Twig::weakrefs);
>> C:/perl/site/5.14.1/lib/XML/Twig.pm:7534:     { my $elt= shift;
>> C:/perl/site/5.14.1/lib/XML/Twig.pm:7535:       return if( $XML::Twig::weakrefs);
...