TYPEMAP
VI	T_VI

INPUT
T_VI	
	if (sv_isa($arg, \"VI\")) {
	    IV tmp = SvIV((SV*)SvRV($arg));
	    $var = ($type) tmp;
	    if (!tmp)
		croak(\"screen no longer exists\");
	}
	else
	    croak(\"$var is not of type ${ntype}\")


OUTPUT
T_VI
	if ($var != 0)
	    newVIrv($arg, $var);
	else
	    sv_setsv($arg, &sv_undef);
