DOCUMENTATION:
  name: product
  version_added: "historical"
  short_description: cartesian product of lists
  description:
    - Combines two lists into one with each element being the product of the elements of the input lists.
    - Creates 'nested loops'. Looping over C(listA) and C(listB) is the same as looping over C(listA | product(listB)).
  notes:
    - This is a passthrough to Python's C(itertools.product)
  positional: _input, _additional_lists, repeat
  options:
    _input:
      description: First list.
      type: list
      required: true
    _additional_lists:  #TODO: *args, N possible additional lists
      description: Additional list for the product.
      type: list
      required: false
    repeat:
      description: Number of times to repeat the product against itself.
      default: 1
      type: int
EXAMPLES: |

  # product => [ [ 1, "a" ], [ 1, "b" ], [ 1, "c" ], [ 2, "a" ], [ 2, "b" ], [ 2, "c" ], [ 3, "a" ], [ 3, "b" ], [ 3, "c" ], [ 4, "a" ], [ 4, "b" ], [ 4, "c" ], [ 5, "a" ], [ 5, "b" ], [ 5, "c" ] ]
  product:  "{{ [1,2,3,4,5] | product(['a', 'b', 'c']) }}"

  # repeat_original => [ [ 1, 1 ], [ 1, 2 ], [ 2, 1 ], [ 2, 2 ] ]
  repeat_original: "{{ [1,2] | product(repeat=2) }}"

  # repeat_product => [ [ 1, "a", 1, "a" ], [ 1, "a", 1, "b" ], [ 1, "a", 2, "a" ], [ 1, "a", 2, "b" ], [ 1, "b", 1, "a" ], [ 1, "b", 1, "b" ], [ 1, "b", 2, "a" ], [ 1, "b", 2, "b" ], [ 2, "a", 1, "a" ], [ 2, "a", 1, "b" ], [ 2, "a", 2, "a" ], [ 2, "a", 2, "b" ], [ 2, "b", 1, "a" ], [ 2, "b", 1, "b" ], [ 2, "b", 2, "a" ], [ 2, "b", 2, "b" ] ]
  repeat_product:  "{{ [1,2] | product(['a', 'b'], repeat=2) }}"

  # domains => [ 'example.com', 'ansible.com', 'redhat.com' ]
  domains: "{{ [ 'example', 'ansible', 'redhat'] | product(['com']) | map('join', '.') }}"

RETURN:
  _value:
    description: List of lists of combined elements from the input lists.
    type: list
    elements: list