}

  // 4. Tests of illegal usages of the API:

  private static final ImmutableList<Double> EMPTY_DATASET = ImmutableList.of();

  public void testScale_zero() {
    assertThrows(IllegalArgumentException.class, () -> Quantiles.scale(0));
  }

  public void testScale_negative() {
    assertThrows(IllegalArgumentException.class, () -> Quantiles.scale(-4));
  }