DOCUMENTATION:
  name: subelements
  version_added: "2.7"
  short_description: retuns a product of a list and it's elements
  positional: _input, _subelement, skip_missing
  description:
    - This produces a product of an object and the subelement values of that object, similar to the subelements lookup. This lets you specify individual subelements to use in a template I(_input).
  options:
    _input:
      description: Original list.
      type: list
      elements: any
      required: yes
    _subelement:
      description: Label of property to extract from original list items.
      type: str
      required: yes
    skip_missing:
      description: If C(True), ignore missing subelements, otherwise missing subelements generate an error.
      type: bool
      default: no

EXAMPLES: |
  # data
  users:
    - groups: [1,2,3]
      name: lola
    - name: fernando
      groups: [2,3,4]

  # user_w_groups =>[ { "groups": [ 1, 2, 3 ], "name": "lola" }, 1 ], [ { "groups": [ 1, 2, 3 ], "name": "lola" }, 2 ], [ { "groups": [ 1, 2, 3 ], "name": "lola" }, 3 ], [ { "groups": [ 2, 3, 4 ], "name": "fernando" }, 2 ], [ { "groups": [ 2, 3, 4 ], "name": "fernando" }, 3 ], [ { "groups": [ 2, 3, 4 ], "name": "fernando" }, 4 ] ]
  users_w_groups: {{ users | subelements('groups', skip_missing=True) }}

RETURN:
  _value:
    description: List made of original list and product of the subelement list.
    type: list
    elements: any