minor comment and name update

Author: Daraan

src/typing_extensions.py

@@ -1799,30 +1799,30 @@ def __parameters__(self):
 else:
     _ConcatenateGenericAlias = typing._ConcatenateGenericAlias
 
-# 3.8-3.9,2
-class _EllipsisDummyType: ...
+# 3.8-3.9.2
+class _EllipsisDummy: ...
 
 # 3.8-3.10
 def _create_concatenate_alias(origin, parameters):
     if parameters[-1] is ... and sys.version_info < (3, 9, 2):
-        # Arguments must be types
-        parameters = parameters[:-1] + (_EllipsisDummyType,)
+        # Hack: Arguments must be types, replace it with one.
+        parameters = parameters[:-1] + (_EllipsisDummy,)
     if sys.version_info >= (3, 10, 2):
         concatenate = _ConcatenateGenericAlias(origin, parameters,
                                         _typevar_types=(TypeVar, ParamSpec),
                                         _paramspec_tvars=True)
     else:
         concatenate = _ConcatenateGenericAlias(origin, parameters)
-    if parameters[-1] is not _EllipsisDummyType:
+    if parameters[-1] is not _EllipsisDummy:
         return concatenate
     # Remove dummy again
-    concatenate.__args__ = tuple(p if p is not _EllipsisDummyType else ...
+    concatenate.__args__ = tuple(p if p is not _EllipsisDummy else ...
                                     for p in concatenate.__args__)
     if sys.version_info < (3, 10):
         # backport needs __args__ adjustment only
         return concatenate
     concatenate.__parameters__ = tuple(p for p in concatenate.__parameters__
-                                        if p is not _EllipsisDummyType)
+                                        if p is not _EllipsisDummy)
     return concatenate