src/transformers/tokenization_utils.py/PreTrainedTokenizer/_create_trie
class PreTrainedTokenizer:    def _create_trie(self, unique_no_split_tokens):
        trie = Trie()
        for token in unique_no_split_tokens:
            if hasattr(self, "do_lower_case") and self.do_lower_case and token not in self.all_special_tokens:
                trie.add(token.lower())
            else:
                trie.add(token)
        self.tokens_trie = trie