return null // The domain is a public suffix.
    }

    val firstLabelOffset =
      if (rule[0][0] == EXCEPTION_MARKER) {
        // Exception rules hold the effective TLD plus one.
        domainLabels.size - rule.size
      } else {
        // Otherwise the rule is for a public suffix, so we must take one more label.
        domainLabels.size - (rule.size + 1)
      }