[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

mypy/main.py

@@ -436,7 +436,7 @@ def add_argument_group(
         if title not in [
             "positional arguments",
             "options",
-            "optional argument" # name in python 3.9
+            "optional argument",  # name in python 3.9
         ]:  # These are built-in names, ignore them.
             if not title[0].isupper():
                 raise ValueError(