Make 2.7.2 compatible with Python 2.7.11+ 

version 3.9.0 

version 3.8.1 

version 3.8.0 

version 3.7.1 

version 3.7.0 

version 3.6.0 

version 3.5.0 

version 3.4.1 

version 3.4.0