types.EllipsisType was added in Python 3.10 (#10719)

stdlib/builtins.pyi

@@ -1905,11 +1905,17 @@ def __import__(
 ) -> types.ModuleType: ...
 def __build_class__(__func: Callable[[], _Cell | Any], __name: str, *bases: Any, metaclass: Any = ..., **kwds: Any) -> Any: ...
 
-# Actually the type of Ellipsis is <type 'ellipsis'>, but since it's
-# not exposed anywhere under that name, we make it private here.
-@final
-@type_check_only
-class ellipsis: ...
+if sys.version_info >= (3, 10):
+    # In Python 3.10, EllipsisType is exposed publicly in the types module.
+    @final
+    class ellipsis: ...
+
+else:
+    # Actually the type of Ellipsis is <type 'ellipsis'>, but since it's
+    # not exposed anywhere under that name, we make it private here.
+    @final
+    @type_check_only
+    class ellipsis: ...
 
 Ellipsis: ellipsis