remove type assertions from util.py

Author: gcmarx

git/util.py

@@ -1200,8 +1200,6 @@ def __getattr__(self, attr: str) -> T_IterableObj:
         return list.__getattribute__(self, attr)
 
     def __getitem__(self, index: Union[SupportsIndex, int, slice, str]) -> T_IterableObj:  # type: ignore[override]
-        assert isinstance(index, (int, str, slice)), "Index of IterableList should be an int or str"
-
         if isinstance(index, int):
             return list.__getitem__(self, index)
         elif isinstance(index, slice):
@@ -1214,8 +1212,6 @@ def __getitem__(self, index: Union[SupportsIndex, int, slice, str]) -> T_Iterabl
         # END handle getattr
 
     def __delitem__(self, index: Union[SupportsIndex, int, slice, str]) -> None:
-        assert isinstance(index, (int, str)), "Index of IterableList should be an int or str"
-
         delindex = cast(int, index)
         if not isinstance(index, int):
             delindex = -1