def tokenize(self, text):
        """
        Tokenizes a piece of text into characters.

        For example, `input = "apple""` wil return as output `["a", "p", "p", "l", "e"]`.

        Args:
            text: A single token or whitespace separated tokens.
                This should have already been passed through *BasicTokenizer*.

        Returns:
            A list of characters.
        """
        if self.normalize_text:
            text = unicodedata.normalize("NFKC", text)

        output_tokens = []
        for char in text:
            if char not in self.vocab:
                output_tokens.append(self.unk_token)
                continue

            output_tokens.append(char)

        return output_tokens

        Tokenizes a piece of text into characters.

        For example, `input = "apple""` wil return as output `["a", "p", "p", "l", "e"]`.

        Args:
            text: A single token or whitespace separated tokens.
                This should have already been passed through *BasicTokenizer*.

        Returns:
            A list of characters.
        
dpkd/transformers/src/transformers/models/bert_japanese/tokenization_bert_japanese.py