title: How can I sum a column of a list?
body: <p>I have a Python array, like so:</p>
  
  <pre><code>[[1,2,3],
   [1,2,3]]
  </code></pre>
  
  <p>I can add the row by doing <code>sum(array[i])</code>, how can I sum a column, using a double for loop?</p>
  
  <p>I.E. for the first column, I could get 2, then 4, then 6.</p>