mypy fixup

Author: jbrockmendel

pandas/core/arrays/_arrow_string_mixins.py

@@ -2,6 +2,7 @@
 
 from typing import (
     TYPE_CHECKING,
+    Any,
     Literal,
 )
 
@@ -14,6 +15,8 @@
     import pyarrow.compute as pc
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+
     from pandas._typing import Self
 
 
@@ -27,6 +30,9 @@ def _convert_int_dtype(self, result):
         # Convert an int-dtype arrow result to an appropriate output type.
         raise NotImplementedError
 
+    def _apply_elementwise(self, func: Callable) -> list[list[Any]]:
+        raise NotImplementedError
+
     def _str_pad(
         self,
         width: int,