TYPEMAP

head *   O_OBJECT

OUTPUT
O_OBJECT
    sv_setref_pv( $arg, "Table::ParentChild::Head", (void *)$var );


INPUT
O_OBJECT
    if( sv_isobject( $arg ) && (SvTYPE(SvRV($arg)) == SVt_PVMG)) {
        $var = ($type) SvIV((SV*)SvRV($arg));
    } else {
        warn( \"${Package}::$func_name() -- $var is not a blessed SV reference\" );
        XSRETURN_UNDEF;
    }