fix compatibility with Python 3.7 (#38)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

.github/workflows/test.yml

@@ -7,12 +7,17 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python_version:
+          - "3"
+          - "3.7"
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python
       uses: actions/setup-python@v2
       with:
-        python-version: 3
+        python-version: ${{ matrix.python_version }}
     - run: pip install .[test] coverage
     - name: Test
       run: coverage run --source=./dargs -m unittest -v && coverage report

dargs/dargs.py

@@ -24,7 +24,12 @@
 from copy import deepcopy
 from enum import Enum
 from textwrap import indent
-from typing import Any, Callable, Dict, Iterable, List, Optional, Union, get_origin
+from typing import Any, Callable, Dict, Iterable, List, Optional, Union
+
+try:
+    from typing import get_origin
+except ImportError:
+    from typing_extensions import get_origin
 
 import typeguard
 

pyproject.toml

@@ -17,6 +17,7 @@ classifiers = [
 ]
 dependencies = [
     "typeguard>=3",
+    'typing_extensions; python_version < "3.8"',
 ]
 requires-python = ">=3.7"
 readme = "README.md"