I would like to use spacemacs for python development, but I see a syntax error on Python 3 constructs, like `print(*(i + 1 for i in range(n))` or `async def foo():`. Adding a shebang to my file (`#!/usr/bin/python3` or `#!/usr/bin/env python3`) does not help.

What configuration changes do I need to make to use a specific python version? Ideally per-project or per-file, but global is better than nothing. I have 2.7 and 3.4 installed system-wide, and 3.5 in `~/local` (`~/local/bin` is in my `$PATH`).