Python 2.7 and 3.4, and 3.5 are end of life. They are no longer
receiving bug fixes, including for security issues.

For a list of supported and EOL Pythons, see:

Supported: https://devguide.python.org/#status-of-python-branches
EOL: https://devguide.python.org/devcycle/#end-of-life-branches

Removing support for EOL Pythons will reduce testing and maintenance
resources while allowing the library to move towards a modern Python 3
style.

Next steps

• Do one additional release that supports Python 2.7 to include recent changes
• Create a "1.x" or "python2.7-support" branch to allow ongoing Python 2 maintenance
• Bump the major version number on the master branch (not necessary)
• Review and merge PR Drop support for EOL Pythons #281
• Do another release for Python 3+