title: What is the purpose of "a and a or b"?
body: <p>I came across the following code in <a href="https://github.com/ipython/ipython/blob/master/IPython/core/magics/basic.py#L297" rel="noreferrer">ipython</a>:</p>
  
  <pre><code>oname = args and args or '_'
  </code></pre>
  
  <p>What is the point of that? Why not use just <code>args or '_'</code>? </p>