anchor.diff:  [cols="<,<",options="header",]
   |=======================================================================
   |Parameter |Description
  +|`k` |sets the maximum number of documents retrieved per query. This value will act in place of the usual `size` parameter 
  +in the query. Defaults to 10.
   |`normalize` | If set to `true`, this metric will calculate the https://en.wikipedia.org/wiki/Discounted_cumulative_gain#Normalized_DCG[Normalized DCG].
   |=======================================================================
   
  
positive.code: [cols="<,<",options="header",]
  |=======================================================================
  |Parameter |Description
  |`relevant_rating_threshold` |Sets the rating threshold above which documents are considered to be
  "relevant". Defaults to `1`.
  |`ignore_unlabeled` |controls how unlabeled documents in the search results are counted.
  If set to 'true', unlabeled documents are ignored and neither count as relevant or irrelevant. Set to 'false' (the default), they are treated as irrelevant.
  
negative.code:     }],
      "metric": {
         "dcg": {
              "k" : 20,
              "normalize": false
         }
      }
  