title: Multiply tuple elements if the first element in a tuple matches else ignore
body: <p>I have a list of tuples like below </p>
  
  <pre><code>[(0, 33), (3, 26), (4, 95), (0, 28), (1, 12), (2, 3), (4, 69)]
  </code></pre>
  
  <p>I want to multiply the second elements of the tuple IF the first element matches (once or more); if not I ignore the tuple. So, the output should be</p>
  
  <pre><code>33 * 28 + 95 * 69 = 7479
  </code></pre>
  
  <p>Currently, I am doing the following :</p>
  
  <ol>
  <li>Using a counter to check the existence of the first elements of the tuple.</li>
  <li>Iterate over the collection to see if there exist 1-element tuples or more; ignore the 1-element ones </li>
  <li>Iteratively add the non 1-element tuples to a dictionary and update multiply</li>
  <li>Use the <code>sum</code> function over the <code>values</code> of the dictionary</li>
  </ol>
  
  <p>I wonder if there's a pythonic way to reduce this. I am pretty sure I am complicating matters here.</p>