title: extra empty element when removing an element from a tuple
body: <p>I have a question about the following python outcome.
  Suppose I have a tuple :</p>
  
  <pre><code>a = ( (1,1), (2,2), (3,3) )
  </code></pre>
  
  <p>I want to remove <code>(2,2)</code>, and I'm doing this with the following code:</p>
  
  <pre><code> tuple([x for x in a if x != (2,2)])
  </code></pre>
  
  <p>This works fine, the result is: <code>( (1,1), (3,3) )</code>, just as I expect.</p>
  
  <p>But suppose I start from <code>a = ( (1,1), (2,2) )</code></p>
  
  <p>and use the same tuple() command, the result is  <code>( (1,1), )</code> while I would expect it to be <code>((1,1))</code></p>
  
  <p>In short</p>
  
  <pre><code>&gt;&gt;&gt; a = ( (1,1), (2,2), (3,3) )
  &gt;&gt;&gt; tuple([x for x in a if x != (2,2)])
  ((1, 1), (3, 3))
  &gt;&gt;&gt; a = ( (1,1), (2,2) )
  &gt;&gt;&gt; tuple([x for x in a if x != (2,2)])
  ((1, 1),)
  </code></pre>
  
  <p>Why the comma and empty element in the second case? And how do I get rid of it?</p>
  
  <p>Thanks!</p>