Drop Python 2.7/3.5 support, code refactoring (#104)

.github/workflows/tox.yml

@@ -14,5 +14,5 @@ jobs:
         with:
           python-version: ${{ matrix.python }}
       - run: pip install --upgrade pip
-      - run: pip install pylint==2.8.1 "tox<4"
+      - run: pip install "tox<4"
       - run: tox -e py

.pre-commit-config.yaml

@@ -0,0 +1,14 @@
+# File introduces automated checks triggered on git events
+# to enable run `pip install pre-commit && pre-commit install`
+
+repos:
+  - repo: local
+    hooks:
+      - id: black
+        name: black
+        description: "Black: The uncompromising Python code formatter"
+        entry: black
+        language: python
+        minimum_pre_commit_version: 2.9.2
+        require_serial: true
+        types_or: [ python, pyi ]