---
- name: Block Mapping with Missing Values
  from: NimYAML tests
  tags: explicit-key mapping
  yaml: |
    ? a
    ? b
    c:
  tree: |
    +STR
     +DOC
      +MAP
       =VAL :a
       =VAL :
       =VAL :b
       =VAL :
       =VAL :c
       =VAL :
      -MAP
     -DOC
    -STR
  json: |
    {
      "a": null,
      "b": null,
      "c": null
    }
  dump: |
    a:
    b:
    c: