nargs could be None in argparse.ArgumentParser.add_argument (#10509)

stdlib/argparse.pyi

@@ -85,7 +85,7 @@ class _ActionsContainer:
         self,
         *name_or_flags: str,
         action: _ActionStr | type[Action] = ...,
-        nargs: int | _NArgsStr | _SUPPRESS_T = ...,
+        nargs: int | _NArgsStr | _SUPPRESS_T | None = None,
         const: Any = ...,
         default: Any = ...,
         type: Callable[[str], _T] | FileType = ...,