how to use TikTokenizer during Training?

[bugm]

Hello,
I noticed that ML now support TikTokenizer by setting the --tokenizer-type argument. But I do not know what i should set with --tokenizer-model. I have checked the source code and find that we should pass a json file, and the function below will convert the json file to Tiktoken format.

Megatron-LM/megatron/training/tokenizer/tokenizer.py

Line 581 in 772faca

def reload_mergeable_ranks(path: str, max_vocab: Optional[int] = None) -> Dict[bytes, int]:

The comment says " Reload our tokenizer JSON file and convert it to Tiktoken format." What does "our tokenizer JSON" means? which format should the json file be?