title: Pythonic / itertools way to go through a dict?
body: <pre><code>def reportCSV(t):
      ret = ''
      for ev in t:
          for p in t[ev]:
              for w in t[ev][p]:
                  ret += ','.join((ev, p, w, t[ev][p][w])) + '\n'
      return ret
  </code></pre>
  
  <p>What is a more pythonic way to do this, e.g. using itertools or the like?</p>
  
  <p>In this case I'm just writing it out to a CSV file. 
  t is a dict
  t[ev] is a dict
  t[ev][p] is a dict
  t[ev][p][w] is a float</p>
  
  <p>I'm not sure how I'd use itertools.product in this case.</p>