int set( SV *rv, SV *in ) {
    O *o = *(O**)SvPV( SvRV( rv ), PL_na );
    o->sv = newSVsv( in );
    printf( "S:rv;%p o:%p o->sv:%p\n", rv, o, o->sv );
    return 1;
}

SV *get( SV *rv ) {
    O *o = *(O**)SvPV( SvRV( rv ), PL_na );
    printf( "G:rv;%p o:%p o->sv:%p\n", rv, o, o->sv );
    return newSVsv( o->sv );
}

S:rv;0x8d1c9f4 o:0x87736f4 o->sv:0x8d1d374
G:rv;0x8641564 o:0x87736f4 o->sv:0x8d1d374