Adding testing

Adding testing with flask8, pre-commit and pyproject

.flake8

@@ -0,0 +1,5 @@
+[flake8]
+ignore = E203, E266, E501, W503, F403, F401
+max-line-length = 79
+max-complexity = 18
+select = B,C,E,F,W,T4,B9

.pre-commit-config.yaml

@@ -5,8 +5,16 @@ repos:
       hooks:
           - id: trailing-whitespace
             language: python
+    - repo: https://github.com/ambv/black
+      rev: stable
+      hooks:
+          - id: black
+            language_version: python3.8
+    - repo: https://gitlab.com/pycqa/flake8
+      rev: 3.7.9
+      hooks:
+          - id: flake8
     - repo: https://github.com/asottile/blacken-docs
       rev: v1.8.0
       hooks:
           - id: blacken-docs
-        additional_dependencies: [black==19.3b0]

pyproject.toml

@@ -0,0 +1,16 @@
+[tool.black]
+line-length = 79
+include = '\.pyi?$'
+exclude = '''
+/(
+    \.git
+  | \.hg
+  | \.mypy_cache
+  | \.tox
+  | \.venv
+  | _build
+  | buck-out
+  | build
+  | dist
+)/
+'''