src/transformers/tokenization_utils_fast.py/PreTrainedTokenizerFast/get_added_vocab
class PreTrainedTokenizerFast:    def get_added_vocab(self) -> Dict[str, int]:
        """
        Returns the added tokens in the vocabulary as a dictionary of token to index.

        Returns:
            `Dict[str, int]`: The added tokens.
        """
        base_vocab = self._tokenizer.get_vocab(with_added_tokens=False)
        full_vocab = self._tokenizer.get_vocab(with_added_tokens=True)
        added_vocab = {tok: index for tok, index in full_vocab.items() if tok not in base_vocab}
        return added_vocab