anchor.diff:  
        - do:
          ... test definitions ...
  +....
   
   All tests in the file should be skipped if: `min <= current <= max`.
   
  
positive.code: 
  The `do` operator calls a method on the client. For instance:
  
      - do:
          cluster.health:
              level: shards
  
  The response from the `do` operator should be stored in the `response` var, which
  is reset (1) at the beginning of a file or (2) on the next `do`.
  
negative.code:             type:  test
              id:    $id    # replace `$id` with the stashed value
      - match: { _id: $id } # the returned `response._id` matches the stashed `id`
  ....
  
  The stash should be reset at the beginning of each test file.
  
  