Andrew Barnert writes:
If you just run python (off the path), unless -3 is specified, in which case you run python3 instead. Doesn't that over all known distros, third-party installations, and pristine local installs of 3.x?
I don't know if you consider MacPorts a "distro", but no, it doesn't install a /opt/local/bin/python3 link. You need to specify the minor version.