@type t() ::
  (((((((((((((((((((((:missing | :offset_x) | :offset_y) | :radius) | :spread)
                   | :color)
                  | :refraction_radius)
                 | :specular_angle)
                | :specular_intensity)
               | :chromatic_aberration)
              | :splay)
             | :refraction_intensity)
            | :start_radius)
           | :start_offset_x)
          | :start_offset_y)
         | :end_offset_x)
        | :end_offset_y)
       | :noise_size_x)
      | :noise_size_y)
     | :density)
    | :effect_opacity)
   | :secondary_color)
  | integer()