title: Python: what is the difference between (1,2,3) and [1,2,3], and when should I use each?
body: <p>In many places, <code>(1,2,3)</code> (a tuple) and <code>[1,2,3]</code> (a list) can be used interchangeably.</p>
  
  <p>When should I use one or the other, and why?</p>