title: How to add up the specific values of the OrderedDic elements of a list?
body: <p>If there is:</p>
  <pre><code>random_list = [OrderedDict([('num1',1.0), ('num2', 2.0), ('num3', 3.0)]),OrderedDict([('num1',10.0), ('num2', 20.0), ('num3', 30.0])]
  </code></pre>
  <ol>
  <li>How to add up the values of num2 together? (2.0 + 20.0 = 22.0)</li>
  <li>How to add up the values of num2 and num3 together? (2.0 + 20.0 + 3.0 + 30.0= 55.0)</li>
  </ol>
  <p>In none of the above, sum() should be used.</p>
  <p>Thanks.</p>