pickle: improve positional-arg accuracy in py39 and others (#4273)

Although technically data in loads is not positional-only in py38, but
we decided that that doesn't matter

Co-authored-by: hauntsaninja <>

stdlib/2and3/pickle.pyi

@@ -32,7 +32,7 @@ if sys.version_info >= (3, 8):
         errors: str = ..., buffers: Optional[Iterable[Any]] = ...
     ) -> Any: ...
     def loads(
-        data: bytes, *, fix_imports: bool = ..., encoding: str = ...,
+        __data: bytes, *, fix_imports: bool = ..., encoding: str = ...,
         errors: str = ..., buffers: Optional[Iterable[Any]] = ...
     ) -> Any: ...
 elif sys.version_info >= (3, 0):
@@ -79,7 +79,7 @@ class Pickler:
     else:
         def __init__(self, file: IO[bytes], protocol: Optional[int] = ...) -> None: ...
 
-    def dump(self, obj: Any) -> None: ...
+    def dump(self, __obj: Any) -> None: ...
     def clear_memo(self) -> None: ...
     def persistent_id(self, obj: Any) -> Any: ...
 
@@ -95,7 +95,7 @@ class Unpickler:
         def __init__(self, file: IO[bytes]) -> None: ...
 
     def load(self) -> Any: ...
-    def find_class(self, module: str, name: str) -> Any: ...
+    def find_class(self, __module_name: str, __global_name: str) -> Any: ...
     if sys.version_info >= (3, 0):
         def persistent_load(self, pid: Any) -> Any: ...
 

tests/stubtest_whitelists/py3_common.txt

@@ -338,7 +338,6 @@ os._Environ.__init__
 os._Environ.setdefault
 os._wrap_close.__init__
 pickle.Pickler.persistent_id
-pickle.Unpickler.find_class
 pickle.Unpickler.persistent_load
 pipes.Template.copy
 pkgutil.ImpImporter.__init__