---
- name: Spec Example 2.25. Unordered Sets
  from: http://www.yaml.org/spec/1.2/spec.html#id2761758
  tags: spec mapping unknown-tag explicit-key
  yaml: |
    # Sets are represented as a
    # Mapping where each key is
    # associated with a null value
    --- !!set
    ? Mark McGwire
    ? Sammy Sosa
    ? Ken Griff
  tree: |
    +STR
     +DOC ---
      +MAP <tag:yaml.org,2002:set>
       =VAL :Mark McGwire
       =VAL :
       =VAL :Sammy Sosa
       =VAL :
       =VAL :Ken Griff
       =VAL :
      -MAP
     -DOC
    -STR
  json: |
    {
      "Mark McGwire": null,
      "Sammy Sosa": null,
      "Ken Griff": null
    }
  dump: |
    --- !!set
    Mark McGwire:
    Sammy Sosa:
    Ken Griff: