title: Comma separated variable assignment
body: <p>Can someone please explain to me what line 4 is doing?</p>
  
  <pre><code>1 def fib2(n):  # return Fibonacci series up to n
  2 ...     """Return a list containing the Fibonacci series up to n."""
  3...     result = []
  4...     a, b = 0, 1  #this line
  5...     while a &lt; n:
  6...         result.append(a)
  7...         a, b = b, a+b
  8...     return result    
  </code></pre>