anchor.diff:     "book":{
         "properties":{
            "title":{
  -            "type":"string", "similarity":"BM25" 
  +            "type":"string", "similarity":"BM25"
            }
         }
      }
  
positive.code: |`doc_values` |Set to `true` to store field values in a column-stride fashion.
  Automatically set to `true` when the fielddata format is `doc_values`.
  
  |`precision_step` |The precision step (influences the number of terms 
  generated for each number value). Defaults to `16` for `long`, `double`,
  `8` for `short`, `integer`, `float`, and `2147483647` for `byte`.
  
  
negative.code: |`doc_values` |Set to `true` to store field values in a column-stride fashion.
  Automatically set to `true` when the fielddata format is `doc_values`.
  
  |`precision_step` |The precision step (influences the number of terms
  generated for each number value). Defaults to `16`.
  
  |`boost` |The boost value. Defaults to `1.0`.
  