title: How to filter a list of tuples in scala?
body: <p>I have the following list in Scala which I want to filter based on a criteria such that if there are any tuples with duplicate first value ,
  Like from the below example I want to exclude </p>
  
  <pre><code>List((a,1), (a,2)) 
  </code></pre>
  
  <p>since it is having have "a" as duplicate .</p>