var totalExceptionRuleBytes = 0

      fileSystem.source(publicSuffixListDotDat).buffer().use { source ->
        while (!source.exhausted()) {
          var rule: ByteString = source.readUtf8LineStrict().toRule() ?: continue

          if (rule.startsWith(EXCEPTION_RULE_MARKER)) {
            rule = rule.substring(1)
            // We use '\n' for end of value.
            totalExceptionRuleBytes += rule.size + 1