anchor.diff:          }
       ],
       "max_boost": number,
  -    "score_mode": "(mult|max|...)",
  -    "boost_mode": "(mult|replace|...)"
  +    "score_mode": "(multiply|max|...)",
  +    "boost_mode": "(multiply|replace|...)"
   }
   --------------------------------------------------
   
  
positive.code: where `DECAY_FUNCTION` can be "linear", "exp" and "gauss" (see below).
  The `offset` and `decay` parameters are optional.
  
  `offset`::
      If an `offset` is defined, the decay function will only compute a the
      decay function for documents with a distance greater that the defined
      `offset`. The default is 0.
  `decay`::
  
  The `decay` parameter defines how documents are scored at the distance
  given at `scale`. If no `decay` is defined, documents at the distance
  `scale` will be scored 0.5.
  
  For example, your documents might represents hotels and contain a geo
  location field. You want to compute a decay function depending on how
  
negative.code:     "(query|filter)": {},
      "boost": "boost for the whole query",
      "FUNCTION": {},
      "boost_mode":"(multiply|replace|...)"
  }
  --------------------------------------------------
  
  