title: How to sum() the contents of multiple collections.Counter() objects with loop?
body: <p>I have been researching this issue for a while, 
  for solving <strong>'combining'</strong> <strong><em>multiple</em></strong> Counter().object or dicts; But still can`t work it done.
  And I found two reference below:<br/></p>
  
  <ul>
  <li><a href="https://stackoverflow.com/questions/11011756/is-there-any-pythonic-way-to-combine-two-dicts-adding-values-for-keys-that-appe">Is there any pythonic way to combine two dicts (adding values for keys that appear in both)?</a></li>
  <li><a href="https://stackoverflow.com/questions/19356055/summing-the-contents-of-two-collections-counter-objects">Summing the contents of two collections.Counter() objects</a></li>
  </ul>
  
  <p>For example I have many '<em>Counter Type</em>' variable name with order <code>[1 to 100]</code>:</p>
  
  <pre><code>Name:counter_1 Value:Counter({'a':1, 'b':2, 'c':3})
  Name:counter_2 Value:Counter({'b':5, 'c':19, f:17})
  Name:counter_3 Value:Counter({'a':11, 'b':22, 'c':33, 'd':97})
  ...
  Name:counter_100 Value:Counter({'c':55, 'd':22, 'e':63, 'f':21})
  </code></pre>
  
  <p>If I add each of one manually <code>counter_1 + counter_2 + ... + counter_3</code>, it will make me insane.</p>
  
  <p>Is there more elegant or easier way to <strong>sum()</strong> it all?<br/><br/>
  Thanks a million!</p>