Check for black-formatted file. Black files.

We use 21.6b0

Author: rocky

.github/workflows/autoblack.yml

@@ -0,0 +1,30 @@
+# 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 3.9
+        uses: actions/setup-python@v1
+        with:
+          python-version: 3.9
+      - name: Install Black
+        run: pip install 'black==21.6b0'
+      - 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 'rocky@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

.pre-commit-config.yaml

@@ -5,7 +5,7 @@ repos:
     - id: debug-statements
     - id: end-of-file-fixer
 -   repo: https://github.com/psf/black
-    rev: 20.8b1
+    rev: 21.6b0
     hooks:
     - id: black
       language_version: python3

mathics/builtin/datentime.py

@@ -312,7 +312,7 @@ def parse_date_automatic(self, epochtime, etime, evaluation):
         return date
 
     def to_datelist(self, epochtime, evaluation):
-        """ Converts date-time 'epochtime' to datelist """
+        """Converts date-time 'epochtime' to datelist"""
         etime = epochtime.to_python()
 
         form_name = self.get_name()

mathics/builtin/lists.py

@@ -452,7 +452,7 @@ def join_lists(lists):
 
 
 def get_part(varlist, indices):
-    " Simple part extraction. indices must be a list of python integers. "
+    "Simple part extraction. indices must be a list of python integers."
 
     def rec(cur, rest):
         if rest: