src/transformers/models/flaubert/tokenization_flaubert.py/FlaubertTokenizer/preprocess_text
class FlaubertTokenizer:    def preprocess_text(self, text):
        text = text.replace("``", '"').replace("''", '"')
        text = convert_to_unicode(text)
        text = unicodedata.normalize("NFC", text)

        if self.do_lowercase:
            text = text.lower()

        return text