DOCUMENTATION:
  name: unique
  author: Brian Coca (@bcoca)
  version_added: "1.4"
  short_description: set of unique items of a list
  description:
    - Creates a list of unique elements (a set) from the provided input list.
  options:
    _input:
      description: A list.
      type: list
      required: true
  seealso:
    - plugin_type: filter
      plugin: ansible.builtin.difference
    - plugin_type: filter
      plugin: ansible.builtin.intersect
    - plugin_type: filter
      plugin: ansible.builtin.symmetric_difference
    - plugin_type: filter
      plugin: ansible.builtin.union
EXAMPLES: |
  # return only the unique elements of list1
  # list1: [1, 2, 5, 1, 3, 4, 10]
  {{ list1 | unique }}
  # => [1, 2, 5, 3, 4, 10]
RETURN:
  _value:
    description: A list with unique elements, also known as a set.
    type: list