add pre commit to repo

.pre-commit-config.yaml

@@ -0,0 +1,14 @@
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+repos:
+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.4.0
+    hooks:
+    -   id: trailing-whitespace
+    -   id: end-of-file-fixer
+    -   id: check-yaml
+    -   id: check-added-large-files
+-   repo: https://github.com/psf/black
+    rev: 19.3b0
+    hooks:
+    -   id: black

requirements.txt

@@ -31,3 +31,4 @@ z3-solver>=4.8.5.0
 pysha3
 matplotlib
 pythx
+pre-commit