As we announced, we're releasing a new version that is incompatible with Python 2.7. All Python 2.7-related issues/questions are no longer be supported as of v6.1.0.
Our CI (Travis test) no longer perform tests with Python 2 environment. The minimum required Python version is now 3.5+. We're not using/adding any Python 3-specific features such as async/await syntax in our SDK code at the moment but we may in the future. Please upgrade your Python version if you're still on Python 2.x.
See our original announcement: #215