title: Python's lambda with underscore for an argument?
body: <p>What does the following code do?</p>
  
  <pre><code>a = lambda _:True
  </code></pre>
  
  <p>From what I read and tested in the interactive prompt, it seems to be a function that returns always <code>True</code>.</p>
  
  <p>Am I understanding this correctly? I hope to understand why an underscore (<code>_</code>) was used as well. </p>