title: How can I return a tuple with multiple fields from Combiner/Reducer/Aggregator function?
body: <p><a href="http://storm.apache.org/releases/1.0.6/Trident-API-Overview.html" rel="nofollow noreferrer">Here</a> Storm Documentation states: 
  <em>A CombinerAggregator returns a single tuple with a single field as output.</em></p>
  
  <p>What should I do to return a tuple with multiple fields from Combiner function?</p>
  
  <p>I am creating a aggregate function and want to aggregate two or more values from the input tuple and send these two or more fields as output.</p>
  
  <p>I also want to have some fields of the input tuple in output.
  How can I use Combiner Function to get the required output?</p>
  
  <p>Input Tuple to Combiner Aggregator function: </p>
  
  <p><code>("a", "b", "c" , "d")</code></p>
  
  <p>Required Output Tuple: </p>
  
  <p><code>("a", "b", "newValue1", "newValue2", "newValue3")</code></p>
  
  <p>In the past, I tried creating a model in the <code>init()</code> method of CombinerAggregator from the fields of the tuple and returning it from the CombinerAggregator as a output. But I don't feel that's the right solution.
  Does <code>chainedAgg()</code> function works well with this kind of situation?</p>
  
  <p>Any help will be greatly appreciated.</p>