title: Python List comprehension execution order
body: <pre><code>matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
  squared = [[x**2 for x in row] for row in matrix]
  print(squared)
  </code></pre>
  
  <p>In the preceding data structure and list comprehension, what is the order of execution? </p>
  
  <p>Visually it appears to process from right to left. Considering the nested list first has to be access before each of its individual items can be squared.</p>