} else if (u8a[i] === 0xF4) /* F4 80..8F 80..BF 80..BF */ {
      if (i + 3 < len) /* Expect a 2nd, 3rd 3th byte */ {
        if (u8a[i + 1] < 0x80 || u8a[i + 1] > 0x8F) {
          // *message = "After a first byte of F4, expecting 2nd byte between 80 and 8F.";
          // *faulty_bytes = 2;