Add annotations for Prefetch, prefetch_related_objects.

django-stubs/db/models/query.pyi

@@ -122,3 +122,25 @@ class RawQuerySet(Iterable[_T], Sized):
     def prefetch_related(self, *lookups: Any) -> RawQuerySet[_T]: ...
     def resolve_model_init_order(self) -> Tuple[List[str], List[int], List[Tuple[str, int]]]: ...
     def using(self, alias: Optional[str]) -> RawQuerySet[_T]: ...
+
+class Prefetch(object):
+    def __init__(self, lookup, queryset=None, to_attr=None):
+        # `prefetch_through` is the path we traverse to perform the prefetch.
+        self.prefetch_through = lookup
+        # `prefetch_to` is the path to the attribute that stores the result.
+        self.prefetch_to = lookup
+        if queryset is not None and not issubclass(queryset._iterable_class, ModelIterable):
+            raise ValueError('Prefetch querysets cannot use values().')
+        if to_attr:
+            self.prefetch_to = LOOKUP_SEP.join(lookup.split(LOOKUP_SEP)[:-1] + [to_attr])
+
+        self.queryset = queryset
+        self.to_attr = to_attr
+
+    def __getstate__(self) -> Dict[str, Any]: ...
+    def add_prefix(self, prefix: str) -> None: ...
+    def get_current_prefetch_to(self, level: int) -> str: ...
+    def get_current_to_attr(self, level: int) -> Tuple[str,str]: ...
+    def get_current_queryset(self, level) -> Optional[QuerySet]: ...
+
+def prefetch_related_objects(model_instances: Iterable[_T], *related_lookups: str) -> None: ...