anchor.diff:  Setting the `keyed` flag to `true` will associate a unique string key with each bucket and return the ranges as a hash rather than an array:
   
   [source,console,id=range-aggregation-keyed-example]
  ---------------------------------------------------
  -GET /_search
  +----
  +GET sales/_search
   {
     "aggs": {
       "price_ranges": {
  
positive.code:     }
    }
  }
  --------------------------------------------------
  // TESTRESPONSE[skip:test not setup]
  
  [IMPORTANT]
  
negative.code: (expecting raw documents) and the histogram field (that provides summary information) limits the outcome of the aggregation
  to only the doc counts for each bucket.
  
  **Consequently, when executing a range aggregation over a histogram field, no sub-aggregations are allowed.**
  ========
  