title: Create a single element tuple of tuple
body: <p>I just noticed that if you want to create a tuple with single element, being a tuple itself, you cannot do it with constructor <code>tuple</code> only with <code>(,)</code> syntax. Why is that? </p>
  
  <p>Example:</p>
  
  <pre><code>&gt;&gt;&gt; tuple(list('abc'))
  ('a', 'b', 'c')
  &gt;&gt;&gt; tuple(tuple(list('abc')))
  ('a', 'b', 'c')
  &gt;&gt;&gt; (tuple(list('abc')),)
  (('a', 'b', 'c'),)
  </code></pre>
  
  <p>But then it holds for a list</p>
  
  <pre><code>&gt;&gt;&gt; tuple([1],)
  (1,)
  &gt;&gt;&gt; tuple([1])
  (1,)
  </code></pre>