title: Python calculating the sum of rows in a list
body: <p>I would like to write a piece of code which calculates the sum of the elements in each row of a list and returns a new list of the row sums. For example </p>
  
  <pre><code>def row_sums(square):
  
      square = [
         [1, 2, 3, 4],
         [5, 6, 7, 8],
         [9, 10, 11, 12],
         [13, 14, 15, 16]
      ]
      print(row_sums(square))
  </code></pre>
  
  <p>This would give the output of <code>[10, 26, 42, 58]</code> As the sum of the first row equals 10, sum of the second row equals 26 and so on. However I would like to NOT use the built in sum function to do this. How would I go about doing this? Thanks in advance. </p>