title: can we find the data and modify the oprater name from result
body: <p>data:</p>
  
  <pre><code> {
      "_id" : ObjectId("5874a303414af4d70e3c988d"),
      "trade" : "XYZ",
      "sub_trade" : [ 
          "ABC1", 
          "ABC2", 
          "ABC3", 
          "ABC14", 
          "ABC15"
      ]
    }
  </code></pre>
  
  <p>shall we change index of sub_trade to trade value dynamically</p>
  
  <p>accepting output:</p>
  
  <pre><code>{
      "_id" : ObjectId("5874a303414af4d70e3c988d"),
      "trade" : "XYZ",
      "XYZ" : [ 
          "ABC1", 
          "ABC2", 
          "ABC3", 
          "ABC14", 
          "ABC15"
      ]
    }
  </code></pre>
  
  <p>please help me out</p>