title: How to add up 2 list elements to form a new list in python, by one shot?
body: <p>I've defined 2 lists, n1 and n2:</p>
  
  <pre><code>In [1]: n1=[1,2,3]
  
  In [2]: n2=[4,5,6]
  
  In [3]: n1+n2
  Out[3]: [1, 2, 3, 4, 5, 6]
  
  In [4]: n1+=n2
  
  In [5]: n1
  Out[5]: [1, 2, 3, 4, 5, 6]
  </code></pre>
  
  <p>Well, what I expected to do is to get a new list:
  n3=[5,7,9] as summary of each elements in n1 and n2.</p>
  
  <p>I don't wish to write a for loop to do this routine job. 
  Does python operator or library support a one-shot call to do this?</p>