feat: fieldsets typing (#195)

Author: lukasvinclav

src/unfold/typing.py

@@ -17,4 +17,7 @@ def __call__(self, *args, **kwargs):
         pass
 
 
-FieldsetsType = List[Tuple[Union[str, None], Dict[str, Any]]]
+FieldsetsType = Union[
+    List[Tuple[Union[str, None], Dict[str, Any]]],
+    Tuple[Tuple[Union[str, None], Dict[str, Any]]],
+]