diff --git a/.github/workflows/autoblack.yml b/.github/workflows/autoblack.yml
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+# GitHub Action that uses Black to reformat the Python code in an incoming pull request.
+# If all Python code in the pull request is compliant with Black then this Action does nothing.
+# Othewrwise, Black is run and its changes are committed back to the incoming pull request.
+# https://github.com/cclauss/autoblack
+
+name: autoblack
+on: [pull_request]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - name: Set up Python 3.7
+        uses: actions/setup-python@v1
+        with:
+          python-version: 3.7
+      - name: Install Black
+        run: pip install black
+      - name: Run black --check .
+        run: black --check .
+      - name: If needed, commit black changes to the pull request
+        if: failure()
+        run: |
+          black .
+          git config --global user.name 'autoblack'
+          git config --global user.email 'cclauss@users.noreply.github.com'
+          git remote set-url origin https://x-access-token:${{ secrets.GITHUB_TOKEN }}@github.com/$GITHUB_REPOSITORY
+          git checkout $GITHUB_HEAD_REF
+          git commit -am "fixup: Format Python code with Black"
+          git push