How to add tokens to tokenizer?

[abs-xyz]

I want to add some tokens like [BOST] to the tokenizer so that it does not split these.

How can I achieve this? Any suggestions are welcome.

Huggingface provides functions like add_tokens but I want to make other changes in the source, so I don't want to use HF.

[humza-sami]

tokenizer.add_special_tokens(["[BOST]"])