objtype: Clarify comment why we call mp_load_method_maybe() for native sub-obj.

py/objtype.c

@@ -152,8 +152,9 @@ STATIC void mp_obj_class_lookup(struct class_lookup_data  *lookup, const mp_obj_
             }
         }
 
-        // Try this for completeness, but all native methods should be statically defined
-        // in locals_dict, and would be handled by above.
+        // Previous code block takes care about attributes defined in .locals_dict,
+        // but some attributes of native types may be handled using .load_attr method,
+        // so make sure we try to lookup those too.
         if (lookup->obj != MP_OBJ_NULL && !lookup->is_type && is_native_type(type) && type != &mp_type_object /* object is not a real type */) {
             mp_load_method_maybe(lookup->obj->subobj[0], lookup->attr, lookup->dest);
             if (lookup->dest[0] != MP_OBJ_NULL) {