anchor.diff:  `output`::
       The string to return, if a suggestion matches. This is very
       useful to normalize outputs (i.e. have them always in the format
  -    `artist - songname`). This is optional.
  +    `artist - songname`). The result is de-duplicated if several documents
  +    have the same output, i.e. only one is returned as part of the
  +    suggest result. This is optional.
   
   `payload`::
       An arbitrary JSON object, which is simply returned in the
  
positive.code:   "suggest" : "Nirvana"
  }
  --------------------------------------------------
  
  [[querying]]
  ==== Querying
  
negative.code:     A positive integer, which defines a weight and allows you to
      rank your suggestions. This field is optional.
  
  NOTE: Even though you are losing most of the features of the
  completion suggest, you can opt in for the shortest form, which even
  allows you to use inside of multi_field. But keep in mind, that you will
  not be able to use several inputs, an output, payloads or weights.
  