anchor.diff:  The get operation gets hashed into a specific shard id. It then gets
   redirected to one of the replicas within that shard id and returns the
   result. The replicas are the primary shard and its replicas within that
  -shard id group. This means that the more replicas we will have, the
  +shard id group. This means that the more replicas we have, the
   better GET scaling we will have.
   
   
  
positive.code: // TEST[setup:twitter]
  
  If you only need one or two fields from the complete `_source`, you can use the `_source_includes`
  & `_source_excludes` parameters to include or filter out that parts you need. This can be especially helpful
  with large documents where partial retrieval can save on network overhead. Both parameters take a comma separated list
  of fields or wildcard expressions. Example:
  
  
negative.code: --------------------------------------------------
  // TESTRESPONSE[s/"_seq_no" : \d+/"_seq_no" : $body._seq_no/ s/"_primary_term" : 1/"_primary_term" : $body._primary_term/]
  
  The above result includes the `_index`, `_id`, and `_version`
  of the document we wish to retrieve, including the actual `_source`
  of the document if it could be found (as indicated by the `found`
  field in the response).
  