TYPEMAP
int64_t	T_IV
EV::Etcd	T_PTROBJ
EV::Etcd::Watch	T_PTROBJ

INPUT
T_PTROBJ
    if (SvROK($arg) && sv_derived_from($arg, \"${ntype}\")) {
        IV tmp = SvIV((SV*)SvRV($arg));
        $var = INT2PTR($type, tmp);
    } else {
        croak(\"$var is not of type ${ntype}\");
    }

OUTPUT
T_PTROBJ
    sv_setref_pv($arg, \"${ntype}\", (void*)$var);
