static determinePositionRelativeTo_(region, seconds) {
    const RelativePosition = shaka.media.RegionObserver.RelativePosition_;

    if (seconds < region.startTime) {
      return RelativePosition.BEFORE_THE_REGION;
    }

    if (seconds > region.endTime) {
      return RelativePosition.AFTER_THE_REGION;
    }

    return RelativePosition.IN_THE_REGION;
  }
Get the relative position of the playhead to |region| when the playhead is
at |seconds|. We treat the region's start and end times as inclusive
bounds.

@template T
@param {T} region
@param {number} seconds
@return {shaka.media.RegionObserver.RelativePosition_}
@private