regionIndicesByTime(time) {
      const indices = [];

      self._value?.forEach(({ start, duration, end }, idx) => {
        if (start === undefined) return false;
        if (start > time) return false;
        if (duration === undefined && end === undefined) indices.push(idx);
        else if ((end ?? start + duration) > time) indices.push(idx);
      });

      return indices;
    }
All regions indices that are active at the given time.
@param {number} time
@returns {Array<number>}