title: How to query values in a dictionary of a dictionary in python?
body: <p>I have a list in <code>Python</code> and it's a dictionary contains a dictionary.</p>
  
  <pre><code>{'METTS MARK': {'salary': 365788, 'po': 1}, 'HARRY POTTER':{'salary': 3233233, 'po': 0}
  </code></pre>
  
  <p>How do I calculate the number of records with <code>'po' = 1</code>?</p>
  
  <p>I tried this:</p>
  
  <pre><code>sum = 0
  for key, values in DIC:
       if values[po] == 1:
          sum = sum + 1
  </code></pre>
  
  <p>But it returns: <code>too many values to unpack</code></p>
  
  <p>Thanks in advance</p>