Add pre-commit config

.pre-commit-config.yaml

@@ -0,0 +1,27 @@
+---
+repos:
+  - repo: https://github.com/ambv/black
+    rev: stable
+    hooks:
+      - id: black
+        language_version: python3.7
+
+  - repo: https://github.com/asottile/blacken-docs
+    rev: v0.5.0
+    hooks:
+      - id: blacken-docs
+        additional_dependencies: [black==19.3b0]
+        language_version: python3.7
+
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.0.0
+    hooks:
+      - id: end-of-file-fixer
+      - id: fix-encoding-pragma
+        args: [--remove]
+      - id: trailing-whitespace
+
+  - repo: https://github.com/asottile/reorder_python_imports
+    rev: v1.8.0
+    hooks:
+      - id: reorder-python-imports