// 4 characters. We have bitsPerChar == 6, charsPerChunk == 4, and bytesPerChunk == 3.
      // We're looking for the smallest charsPerChunk such that bitsPerChar * charsPerChunk is a
      // multiple of 8. A multiple of 8 has 3 low zero bits, so we just need to figure out how many
      // extra zero bits we need to add to the end of bitsPerChar to get 3 in total.
      // The logic here would be wrong for bitsPerChar > 8, but since we require distinct ASCII