style: apply flake8 and black formatting

To check for errors:
$ pre-commit run --all-files

To install as pre-commit hook:
$ pre-commit install

.pre-commit-config.yaml

@@ -0,0 +1,15 @@
+repos:
+-   repo: local
+    hooks:
+    - id: flake8
+      name: flake8
+      language: system
+      entry: flake8
+      types: [python]
+      stages: [commit]
+    - id: black
+      name: black
+      language: system
+      entry: black
+      types: [python]
+      stages: [commit]