private static final ImmutableSet<String> NO_PS =
      ImmutableSet.of("www", "foo.ihopethiswillneverbeapublicsuffix", "x.y.z");

  /**
   * Having a public suffix is equivalent to having a registry suffix, because all registry suffixes
   * are public suffixes, and all public suffixes have registry suffixes.
   */
  private static final ImmutableSet<String> NO_RS = NO_PS;

  private static final ImmutableSet<String> NO_PS =
      ImmutableSet.of("www", "foo.ihopethiswillneverbeapublicsuffix", "x.y.z");

  /**
   * Having a public suffix is equivalent to having a registry suffix, because all registry suffixes
   * are public suffixes, and all public suffixes have registry suffixes.
   */
  private static final ImmutableSet<String> NO_RS = NO_PS;