anchor.diff:                      "metadata": {
                           "category": "things"
                       },
  -                    "retirement": {
  -                        "criteria": "classification_count"
  -                    },
                       "created_at": "2014-02-13T10:11:34Z",
                       "updated_at": "2014-02-13T10:11:34Z",
                       "set_member_subject_count": 100,
  
positive.code:                     "metadata": {
                          "category": "things"
                      },
                      "retirement": {
                          "criteria": "classification_count"
                      },
                      "created_at": "2014-02-13T10:11:34Z",
                      "updated_at": "2014-02-13T10:11:34Z",
                      "set_member_subject_cound": 100,
                      "links": {
                          "project": "1",
                          "workflow": "10"
  
negative.code: *finished_at* is set by the API to a date/time when all subjects for this workflow have been retired.
  
  Three parameters: _grouped_, _prioritized_, and _pairwise_ configure
  how the api chooses subjects for classification. They are all false by default,
  which will give a random selection of subjects from all subject\_sets that
  are part of a workflow. _grouped_ enables selecting subjects from a specific
  subject set. _prioritized_ ensures that users will see subjects in a
  predetermined order. _pairwise_ will select two subjects at a tim for classification.
  
  A workflow's `tasks` is a hash of keys to task definitions.
  
  