 word_index (`int`, *optional*):
                If a batch index is provided in *batch_or_token_index*, this can be the index of the word in the
                sequence.
            sequence_index (`int`, *optional*, defaults to 0):
                If pair of sequences are encoded in the batch this can be used to specify which sequence in the pair (0
                or 1) the provided word index belongs to.

        Returns:
            ([`~tokenization_utils_base.TokenSpan`], *optional*): Span of tokens in the encoded sequence. Returns
            `None` if no tokens correspond to the word. This can happen especially when the token is a special token
            that has been used to format the tokenization. For example when we add a class token at the very beginning
            of the tokenization.
        zDword_to_tokens() is not available when using Python based tokenizersNr