constructor(propertyName, begin, end) {
    super('During', propertyName);

    /**
     * @type {!string}
     */
    this.begin = begin;

    /**
     * @type {!string}
     */
    this.end = end;
  }
@param {!string} propertyName Name of the context property to compare.
@param {!string} begin The begin date in ISO-8601 format.
@param {!string} end The end date in ISO-8601 format.