variable.c:834
static VALUE
generic_ivar_defined(obj, id)
    VALUE obj;
    ID id;
{
    st_table *tbl;
    VALUE val;

    if (!generic_iv_tbl) return Qfalse;
    if (!st_lookup(generic_iv_tbl, obj, (st_data_t *)&tbl)) return Qfalse;
    if (st_lookup(tbl, id, &val)) {
	return Qtrue;
    }
    return Qfalse;
}
