On which interpreter is used, you can control this with (IIRC) something
like
port select --set python3 python3.6
port select --set python2 python2.7
port select --set python python2
# or "port select --set python python3" if you like
It's most flexible to say #!/usr/bin/env python2 or #!/us
In short, most stuff works with 2 and 3, and you should use 3. You can
install both, they're independent. virtualenvs are your friend. Also,
"import this" if you haven't already :)
In full, it's quite complex. See
https://wiki.python.org/moin/Python2orPython3
For most features and least hass
