Exclude broken typing-extensions version + fix import

CHANGES.md

@@ -14,6 +14,8 @@
 - Parsing support has been added for unparenthesized walruses in set literals, set
   comprehensions, and indices (#2447).
 - Pin `setuptools-scm` build-time dependency version (#2457)
+- Exclude typing-extensions version 3.10.0.1 due to it being broken on Python 3.10
+  (#2460)
 
 ### _Blackd_
 

setup.py

@@ -79,7 +79,10 @@ def get_long_description() -> str:
         "regex>=2020.1.8",
         "pathspec>=0.9.0, <1",
         "dataclasses>=0.6; python_version < '3.7'",
-        "typing_extensions>=3.10.0.0; python_version < '3.10'",
+        "typing_extensions>=3.10.0.0",
+        # 3.10.0.1 is broken on at least Python 3.10,
+        # https://github.com/python/typing/issues/865
+        "typing_extensions!=3.10.0.1; python_version >= '3.10'",
         "mypy_extensions>=0.4.3",
     ],
     extras_require={

src/black/handle_ipynb_magics.py

@@ -1,15 +1,19 @@
 """Functions to process IPython magics with."""
+
 from functools import lru_cache
 import dataclasses
 import ast
-from typing import Dict
+from typing import Dict, List, Tuple, Optional
 
 import secrets
-from typing import List, Tuple
+import sys
 import collections
 
-from typing import Optional
-from typing_extensions import TypeGuard
+if sys.version_info >= (3, 10):
+    from typing import TypeGuard
+else:
+    from typing_extensions import TypeGuard
+
 from black.report import NothingChanged
 from black.output import out