DOCUMENTATION:
  name: contains
  author: Ansible Core
  version_added: "2.4"
  short_description: does the list contain this element
  description:
    - Checks the supplied element against the input list to see if it exists within it.
  options:
    _input:
      description: List of elements to compare.
      type: list
      elements: raw
      required: True
    _contained:
      description: Element to test for.
      type: raw
      required: True
EXAMPLES: |
  # simple expression
  {{ listofthings is contains('this') }}

  # as a selector
  - action: module=doessomething
    when: lacp_groups|selectattr('interfaces', 'contains', 'em1')|first).master
    vars:
      lacp_groups:
        - master: lacp0
          network: 10.65.100.0/24
          gateway: 10.65.100.1
          dns4:
            - 10.65.100.10
            - 10.65.100.11
          interfaces:
            - em1
            - em2

        - master: lacp1
          network: 10.65.120.0/24
          gateway: 10.65.120.1
          dns4:
            - 10.65.100.10
            - 10.65.100.11
          interfaces:
              - em3
              - em4
RETURN:
  _value:
    description: Returns C(True) if the specified element is contained in the supplied sequence, C(False) otherwise.
    type: boolean