B::MAGIC	T_MG_OBJ
B::SV		T_SV_OBJ

INPUT
T_MG_OBJ
	if (SvROK($arg)) {
	    IV tmp = SvIV((SV*)SvRV($arg));
	    $var = INT2PTR($type,tmp);
	}
	else
	    croak(\"$var is not a reference\")