title: Group and add a list in kotlin
body: <p>How do I group a list and add its values in Kotlin ?.</p>
  
  <pre><code>List =  [0]("06",80.30, 30 , 20 ,"ProductA","CANDY")
          [1]("06", 2.5 , 9 , 6 ,"ProductB","CANDY")
          [2]("07", 8 , 5.7 , 1 ,"ProductC","BEER")
          [3]("08", 10 , 2.10 , 40 ,"ProductD","PIZZA")
  </code></pre>
  
  <p>and get the next result</p>
  
  <pre><code>Result = ("06",82.8, 39 , 26,"CANDY")
           ("07", 8 , 5.7 , 1,"BEER")
           ("08", 10 , 2.10 , 40,"PIZZA")
  </code></pre>
  
  <p>I would greatly appreciate your help.</p>