// choosing to turn .precomputed() into a no-op in GWT, because it doesn't
    // seem to be a worthwhile tradeoff in a browser.
    return matcher;
  }

  static String formatCompact4Digits(double value) {
    return toPrecision(value, 4);
  }

  @JsMethod(name = "Number.prototype.toPrecision.call", namespace = JsPackage.GLOBAL)
  private static native String toPrecision(double value, int precision);

     * `get()`, but that is vanishingly unlikely.
     */
    return ref == null ? Optional.absent() : Optional.fromNullable(enumClass.cast(ref.get()));
  }

  static String formatCompact4Digits(double value) {
    return String.format(Locale.ROOT, "%.4g", value);
  }

  static boolean stringIsNullOrEmpty(@CheckForNull String string) {
    return string == null || string.isEmpty();
  }

  /**

    TimeUnit unit = chooseUnit(nanos);
    double value = (double) nanos / NANOSECONDS.convert(1, unit);

    // Too bad this functionality is not exposed as a regular method call
    return Platform.formatCompact4Digits(value) + " " + abbreviate(unit);
  }

  private static TimeUnit chooseUnit(long nanos) {
    if (DAYS.convert(nanos, NANOSECONDS) > 0) {
      return DAYS;
    }