title: How is `var[:] = []` different from `var = []`?
body: <p>I normally understand how slices behave to the left and right of the assignment operator.</p>
  
  <p>However, I've seen this in the Python (3.8.0) manual and trying to figure out what I'm missing.</p>
  
  <blockquote>
    <h1>clear the list by replacing all the elements with an empty list</h1>
    
    <p>letters[:] = []</p>
  </blockquote>
  
  <p>How's that different from just <code>letters = []</code>?</p>
  
  <p>(It's not easy to search for <code>[:]</code> as stackoverflow thinks you're looking for a tag.  So, if there is already an answer I couldn't locate it.)</p>
  
  <p>I see some rather irrelevant answers.  So, to hopefully clarity, the question is not about what the <code>[:]</code> slice means, rather about assigning the <em>empty</em> list to one.</p>