language: python
python:
  - "2.7"
  - "3.5"
install:
  - python -m pip install tox
script:
  - python -m tox

language: python
matrix:
  include:
    - python: 2.7
      env: TOXENV=py27
    - python: 3.5
      env: TOXENV=py35
install:
  - python -m pip install tox
script:
  - python -m tox

Use a testing matrix for testing both versions.
Use a testing matrix for testing both versions.
