Travis CI: Lint for Python syntax errors and undefined names

.travis.yml

@@ -1,4 +1,20 @@
 language: generic
+matrix:
+ include:
+ - name: "generic tests"
+ - name: "flake8 lint on Python 2.7"
+ language: python
+ python: 2.7
+ install: pip install flake8
+ script: flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+ - name: "flake8 lint on Python 3.7"
+ dist: xenial # required for Python >= 3.7
+ language: python
+ python: 3.7
+ install: pip install flake8
+ script: flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+ allow_failures:
+ - python 3.7
 install:
  - sudo apt-get install -y python-pip
  - sudo pip install pep8