title: Add element to set in the form of list comprehension in Python
body: <p>I have a list of sets. I want to add an element to each of these sets, and I want to do this with list comprehension. This is what I have tried:</p>
  
  <pre><code>In [1]: sets1 = [set()]
  
  In [2]: sets2 = [{1,2}, {1,2,3}]
  
  In [3]: [e.add(0) for e in sets1]
  Out[3]: [None]
  
  In [4]: [e.add(0) for e in sets2]
  Out[4]: [None, None]
  </code></pre>
  
  <p>My desired output is:</p>
  
  <pre><code>[{0}]
  [{1,2,0}, {1,2,3,0}]
  </code></pre>
  
  <p>Why does the above code return <code>None</code> instead of an addition of elements to the list, and how I can make this work?</p>