Model missing readline history entries as optional strings (#16524)

Author: xiehuanyi

stdlib/readline.pyi

@@ -1,7 +1,7 @@
 import sys
 from _typeshed import StrOrBytesPath
 from collections.abc import Callable, Sequence
-from typing import Literal, TypeAlias
+from typing import Literal, SupportsIndex, TypeAlias
 
 if sys.platform != "win32":
     _Completer: TypeAlias = Callable[[str, int], str | None]
@@ -19,7 +19,7 @@ if sys.platform != "win32":
     def set_history_length(length: int, /) -> None: ...
     def clear_history() -> None: ...
     def get_current_history_length() -> int: ...
-    def get_history_item(index: int, /) -> str: ...
+    def get_history_item(index: SupportsIndex, /) -> str | None: ...
     def remove_history_item(pos: int, /) -> None: ...
     def replace_history_item(pos: int, line: str, /) -> None: ...
     def add_history(string: str, /) -> None: ...