from transformers import PreTrainedTokenizerFast
fast_tokenizer = PreTrainedTokenizerFast(tokenizer_object=tokenizer)

This object can now be used with all the methods shared by the 🤗 Transformers tokenizers! Head to the tokenizer
page for more information.
Loading from a JSON file
In order to load a tokenizer from a JSON file, let's first start by saving our tokenizer:
thon

tokenizer.save("tokenizer.json")