title: What is the syntax rule for having trailing commas in tuple definitions?
body: <p>In the case of a single element tuple, the trailing comma is required.</p>
  
  <pre><code>a = ('foo',)
  </code></pre>
  
  <p>What about a tuple with multiple elements? It seems that whether the trailing comma exists or not, they are both valid. Is this correct? Having a trailing comma is easier for editing in my opinion. Is that a bad coding style?</p>
  
  <pre><code>a = ('foo1', 'foo2')
  b = ('foo1', 'foo2',)
  </code></pre>