function Duration(months, days, nanoseconds) {
  /**
   * Gets the number of months.
   * @type {Number}
   */
  this.months = months;
  /**
   * Gets the number of days.
   * @type {Number}
   */
  this.days = days;
  /**
   * Gets the number of nanoseconds represented as a <code>int64</code>.
   * @type {Long}
   */
  this.nanoseconds = typeof nanoseconds === 'number' ? Long.fromNumber(nanoseconds) : nanoseconds;
}