cleanup callable type hint with typevar

quixstreams/dataframe/dataframe.py

@@ -13,6 +13,7 @@
     Literal,
     Optional,
     Tuple,
+    TypeVar,
     Union,
     cast,
     overload,
@@ -1324,31 +1325,12 @@ def _drop(value: Dict, columns: List[str], ignore_missing: bool = False):
                 raise
 
 
-@overload
-def _as_metadata_func(
-    func: ApplyCallbackStateful,
-) -> ApplyWithMetadataCallbackStateful: ...
-
-
-@overload
-def _as_metadata_func(
-    func: FilterCallbackStateful,
-) -> FilterWithMetadataCallbackStateful: ...
-
-
-@overload
-def _as_metadata_func(
-    func: UpdateCallbackStateful,
-) -> UpdateWithMetadataCallbackStateful: ...
+T = TypeVar("T")
 
 
 def _as_metadata_func(
-    func: Union[ApplyCallbackStateful, FilterCallbackStateful, UpdateCallbackStateful],
-) -> Union[
-    ApplyWithMetadataCallbackStateful,
-    FilterWithMetadataCallbackStateful,
-    UpdateWithMetadataCallbackStateful,
-]:
+    func: Callable[[Any, State], T],
+) -> Callable[[Any, Any, int, Any, State], T]:
     @functools.wraps(func)
     def wrapper(
         value: Any, _key: Any, _timestamp: int, _headers: Any, state: State
@@ -1359,9 +1341,9 @@ def wrapper(
 
 
 def _as_stateful(
-    func: ApplyWithMetadataCallbackStateful,
+    func: Callable[[Any, Any, int, Any, State], T],
     processing_context: ProcessingContext,
-) -> ApplyWithMetadataCallback:
+) -> Callable[[Any, Any, int, Any], T]:
     @functools.wraps(func)
     def wrapper(value: Any, key: Any, timestamp: int, headers: Any) -> Any:
         ctx = message_context()