Is it safe to assume tokenizer does not change after initialization?

🤗Tokenizers
1

Hi, I find many attributes in tokenizer are very expensive to compute, e.g.

    def __len__(self):
        """
        Size of the full vocabulary with the added tokens. Counts the `keys` and not the `values` because otherwise if
        there is a hole in the vocab, we will add tokenizers at a wrong index.
        """
        return len(set(self.get_vocab().keys()))

Therefore, I want to cache the results of some attributes on tokenizer. I do see some functions that can change a tokenizer, but I find they are only used during initialization, and these methods are marked as private by an _ prefix, e.g. _update_trie/_add_tokens .

Is it safe to assume a tokenizer does not change after initialization? If not, what are some typical use cases to change a tokenizer after initialization?