Yang leaf of fixed length

Hi! I have the following group in my yang model.
I need to set checksum length to 64 (fixed)

grouping CHECKSUM-GROUP-10 {
      description "checksum helper group";
      leaf checksum-10 {
        type string{
          length "64";
        mandatory true;
          "List of checksums (max 10)";

This errors out as max is set to None in range

[(64, None)]
**TypeError: '<=' not supported between instances of 'int' and 'NoneType'**
> /auto/cafy/release/21.11.10/rhel7-21.11.10/lib/python3.6/site-packages/ydk/providers/_validator.py(147)_dm_validate_value()
-> if len(value) >= pmin and len(value) <= pmax:

I then tried (length “64…64”). But it errors (yang:328: error: length error: “64” is not larger than “64”)

Can someone please help with this?

I believe that YDK questions/issues should be addressed by the YDK GitHub project, not by the ConfD user community.