//'cmd': ['/usr/local/bin/python', '-u', '$file'],
(Add the //.)4. Add this line: 'cmd': ['/usr/bin/env', 'python', '-u', '$file'],
(Don't forget the comma.)5. Save the file, open a simple Python2 program, and see if command-B works.'cmd': ['/usr/bin/env', 'python3', '-u', '$file'],
4. Save as Python3.5. If you ever need to edit this file again, you'll find it in ~/Library/Application Support/Sublime Text 2/Packages/User.