sig
  type t =
      [ `Hexadecagonal
      | `Hexagonal
      | `Mono
      | `Native
      | `Octagonal
      | `Quad
      | `Stereo
      | `Stereo_downmix
      | `Surround
      | `_2_1
      | `_2_2
      | `_2point1
      | `_3point1
      | `_4point0
      | `_4point1
      | `_5point0
      | `_5point0_back
      | `_5point1
      | `_5point1_back
      | `_6point0
      | `_6point0_front
      | `_6point1
      | `_6point1_back
      | `_6point1_front
      | `_7point0
      | `_7point0_front
      | `_7point1
      | `_7point1_wide
      | `_7point1_wide_back ]
end