py34: {env:TOXPYTHON:python3.4}
py35: {env:TOXPYTHON:python3.5}
py36: {env:TOXPYTHON:python3.6}
py37: {env:TOXPYTHON:python3.7}
py34: {env:TOXPYTHON:python3.4}
py35: {env:TOXPYTHON:python3.5}
py36: {env:TOXPYTHON:python3.6}
py37: {env:TOXPYTHON:python3.7}