title: Removing nested dict items with dict comprehension
body: <p>I have two dicts:</p>
  
  <pre><code>blocked = {'-5.00': ['121', '381']}
  all_odds = {'-5.00': '{"121":[1.85,1.85],"381":[2.18,1.73],"16":[2.18,1.61],"18":\
              [2.12,1.79]}'}
  </code></pre>
  
  <p>I want to first check whether the <code>.keys()</code> comparision (<code>==</code>) returns <code>True</code>, here it does (both <code>-5.00</code>) then I want to remove all items from <code>all_odds</code> that has the key listed in <code>blocked.values()</code> . </p>
  
  <p>For the above it should result in: </p>
  
  <pre><code>all_odds_final = {'-5.00': '{"16":[2.18,1.61],"18": [2.12,1.79]}'}
  </code></pre>
  
  <p>I tried <code>for loop</code>:</p>
  
  <pre><code>if blocked.keys() == all_odds.keys():
      for value in blocked.values():
          for v in value:
              for val in all_odds.values():
                  val = eval(val)
                  if val.has_key(v):
                      del val[v] 
  </code></pre>
  
  <p>which you know is very ugly plus it's not working properly yet. </p>