constructor(locale, style, direction, unit, expected, pluralrules) {
    this.locale = locale;
    this.style = style;
    this.direction = direction;
    this.unit = unit;
    this.expected = expected;
    this.pluralrules = pluralrules;
  }
@param {string} locale
@param {number} style
@param {number} direction
@param {number} unit
@param {string} expected
@param {string|undefined} pluralrules