title: Is the command python3 simply the OS X variation of py -3?
body: <p>In Learning Python by Mark Lutz he changes the Python version number using variations of the command <code>py -3</code>, which on OS X returns <code>-bash: py: command not found</code>.</p>
  
  <p>I know (via <a href="https://stackoverflow.com/questions/15285592/how-to-set-default-python-version-in-terminal-on-os-x-10-6-8">SO</a>, of course) that I can do it on OS X with <code>python3</code> and I guess I could add an alias in <code>.bash_profile</code> (though not sure what the point would be), but is there anything I'm missing here other than that <code>python3</code> is the way to say <code>py -3</code> in OS X?</p>