anchor.diff:  === URL Parameters
   
   In addition to the standard parameters like `pretty`, the Update By Query API
  -also supports `refresh`, `wait_for_completion`, `wait_for_active_shards`, `timeout`
  +also supports `refresh`, `wait_for_completion`, `wait_for_active_shards`, `timeout`,
   and `scroll`.
   
   Sending the `refresh` will update all shards in the index being updated when
   the request completes. This is different than the Update API's `refresh`
  -parameter which causes just the shard that received the new data to be indexed.
  +parameter, which causes just the shard that received the new data to be indexed.
   Also unlike the Update API it does not support `wait_for`.
   
   If the request contains `wait_for_completion=false` then Elasticsearch will
  
positive.code: 
  The advantage of this API is that it integrates with `wait_for_completion=false`
  to transparently return the status of completed tasks. If the task is completed
  and `wait_for_completion=false` was set on it them it'll come back with a
  `results` or an `error` field. The cost of this feature is the document that
  `wait_for_completion=false` creates at `.tasks/task/${taskId}`. It is up to
  you to delete that document.
  
negative.code: Just as in <<docs-update,Update API>> you can set `ctx.op` to change the
  operation that is executed:
  
  [horizontal]
  `noop`::
  
  Set `ctx.op = "noop"` if your script decides that it doesn't have to make any
  