title: Triple For loop in python, major confusion
body: <pre><code>for i in range(4):
          for j in V[i].customers:
              V[i].message =\
                              dict([(k,array([1,1])) \
                                   for k in V[i]. customers])
  </code></pre>
  
  <p>I dont understand this for structure at all. Could some one explain how this works ?</p>
  
  <p>Also, that <code>=\</code> what does it do?</p>