anchor.diff:  }'
   --------------------------------------------------
   
  -We can also remove a field from the document:
  +Or remove a field from the document:
   
   [source,js]
   --------------------------------------------------
  
positive.code:     }
  }'
  --------------------------------------------------
  If the document does not exist you may want your update script to
  run anyway in order to initialize the document contents using
  business logic unknown to the client. In this case pass the
  new `scripted_upsert` parameter with the value `true`.
  
  [source,js]
  --------------------------------------------------
  
negative.code: [float]
  === Parameters
  
  The update operation supports the following query-string parameters:
  
  [horizontal]
  `retry_on_conflict`::
  
  In between the get and indexing phases of the update, it is possible that
  another process might have already updated the same document.  By default, the
  update will fail with a version conflict exception.  The `retry_on_conflict`
  parameter controls how many times to retry the update before finally throwing
  an exception.
  
  `routing`::
  
  Routing is used to route the update request to the right shard and sets the
  routing for the upsert request if the document being updated doesn't exist.
  Can't be used to update the routing of an existing document.
  
  `parent`::
  
  Parent is used to route the update request to the right shard and sets the
  parent for the upsert request if the document being updated doesn't exist.
  Can't be used to update the `parent` of an existing document.
  
  `timeout`::
  
  Timeout waiting for a shard to become available.
  
  `consistency`::
  
  The write consistency of the index/delete operation.
  
  `refresh`::
  
  Refresh the relevant primary and replica shards (not the whole index)
  immediately after the operation occurs, so that the updated document appears
  in search results  immediately.
  
  `fields`::
  
  Return the relevant fields from the updated document. Specify `_source` to
  return the full updated source.
  
  `version` & `version_type`::
  
  The Update API uses the Elasticsearch's versioning support internally to make
  sure the document doesn't change during the update. You can use the `version`
  parameter to specify that the document should only be updated if it's version
  matches the one specified. By setting version type to `force` you can force
  the new version of the document after update (use with care! with `force`
  there is no guarantee the document didn't change).Version types `external` &
  `external_gte` are not supported.
  
  