function computePositions(dateParts) {
    /**
     * @param {number} index
     * @returns {string}
     */
    function getPartByIndex(index) {
      /** @type {Object.<string,string>} */
      const template = {
        2012: 'year',
        12: 'month',
        20: 'day',
      };
      const key = dateParts[index];
      return template[key];
    }

    return [1, 3, 5].map(getPartByIndex);
  }
@param {ArrayLike.<string>} dateParts
@returns {string[]}