internal fun setLengths(strings: List<String>) {
      if (strings.size != valueCount) {
        invalidLengths(strings)
      }

      try {
        for (i in strings.indices) {
          lengths[i] = strings[i].toLong()
        }
      } catch (_: NumberFormatException) {
        invalidLengths(strings)
      }
    }

    /** Append space-prefixed lengths to [writer]. */