* range set (such as {@code ImmutableRangeSet.of(Range.greaterThan(0))}). Certain operations on
   * such a set can be performed efficiently, but others (such as {@link Set#hashCode} or {@link
   * Collections#frequency}) can cause major performance problems.
   *
   * <p>The returned set's {@link Object#toString} method returns a shorthand form of the set's
   * contents, such as {@code "[1..100]}"}.
   *