assertThrows(IllegalArgumentException.class, () -> Stats.meanOf(ImmutableList.<Number>of()));
    assertThat(Stats.meanOf(ONE_VALUE)).isWithin(ALLOWED_ERROR).of(ONE_VALUE);
    assertThat(Stats.meanOf(POSITIVE_INFINITY)).isPositiveInfinity();
    assertThat(Stats.meanOf(NEGATIVE_INFINITY)).isNegativeInfinity();
    assertThat(Stats.meanOf(NaN)).isNaN();

  public static double meanOf(long... values) {
    checkArgument(values.length > 0);
    double mean = values[0];
    for (int index = 1; index < values.length; index++) {
      double value = values[index];
      if (isFinite(value) && isFinite(mean)) {
        // Art of Computer Programming vol. 2, Knuth, 4.2.2, (15)
        mean += (value - mean) / (index + 1);
      } else {
        mean = calculateNewMeanNonFinite(mean, value);
      }

      // in NaN naturally.
      sumOfProductsOfDeltas +=
          values.sumOfProductsOfDeltas()
              + (values.xStats().mean() - xStats.mean())
                  * (values.yStats().mean() - yStats.mean())
                  * values.count();
    }
    yStats.addAll(values.yStats());
  }

  /** Returns an immutable snapshot of the current statistics. */

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