title: How to sum dict elements
body: <p>In Python,
  I have list of dicts: </p>
  
  <pre><code>dict1 = [{'a':2, 'b':3},{'a':3, 'b':4}]
  </code></pre>
  
  <p>I want one final dict that will contain the sum of all dicts.
  I.e the result will be: <code>{'a':5, 'b':7}</code></p>
  
  <p>N.B: every dict in the list will contain same number of key, value pairs.</p>