Conditional typeguard import based on versions

Author: alexiswl

Diff for: cwl_utils/inputs_schema_gen.py

@@ -11,11 +11,15 @@
 from copy import deepcopy
 from pathlib import Path
 from typing import Any, List, Union, Dict, Optional
-from typing_extensions import TypeGuard  # Not in 3.8 typing module
 from urllib.parse import urlparse
-
 import requests
 
+# Get typeguard from extensions if we're running in python3.8
+if python_version := sys.version_info[:2] < (3, 9):
+    from typing_extensions import TypeGuard  # Not in 3.8 typing module
+else:
+    from typing import TypeGuard
+
 from cwl_utils.loghandler import _logger as _cwlutilslogger
 from cwl_utils.parser import (
     load_document_by_uri,