---
- name: Anchor for empty node
  from: https://github.com/nodeca/js-yaml/issues/301
  tags: alias anchor
  yaml: |
    ---
    a: &anchor
    b: *anchor
  tree: |
    +STR
     +DOC ---
      +MAP
       =VAL :a
       =VAL &anchor :
       =VAL :b
       =ALI *anchor
      -MAP
     -DOC
    -STR
  json: |
    {
      "a": null,
      "b": null
    }
  dump: |
    ---
    a: &anchor
    b: *anchor