title: python: count values of dictionary
body: <p>I'm working with python and I need to find in a dictionary how many values each key has.
  this is my dictionary:</p>
  
  <pre><code> {2: [(1, 1)], 3: [(2, 1), (2, 1)], 4: [(1, 3), (3, 1), (3, 1)], 5: [(1, 4), (2, 3), (2, 3), (4, 1)], 6: [(1, 5), (2, 4), (2, 4), (3, 3), (3, 3)], 7: [(1, 6), (2, 5), (2, 5), (3, 4), (3, 4), (4, 3)], 8: [(2, 6), (2, 6), (3, 5), (3, 5), (4, 4)], 9: [(1, 8), (3, 6), (3, 6), (4, 5)], 10: [(2, 8), (2, 8), (4, 6)], 11: [(3, 8), (3, 8)], 12: [(4, 8)]}
  </code></pre>
  
  <p>I need to find how many values there are for each key:
  so it will be like:</p>
  
  <pre><code>{2: 1, 3: 2, 4: 3, 5: 4, 6: 5, 7: 6, 8: 5, 9: 4, 10: 3, 11: 2, 12: 1}
  </code></pre>
  
  <p>I've tried to make it work for a long time
  thanks in advance</p>