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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fix_mispelled_day(cls, timestr):
 """fix mispelled day when written in english :return: `None` if the day was not modified, the new date otherwise """

        day_extraction = cls.START_WITH_DAY_OF_WEEK.match(timestr)
        if day_extraction is not None:
            day = day_extraction.group(1).lower()
            if len(day) == 3:
                dataset = DAYS_ABBR
            else:
                dataset = DAYS
            if day not in dataset:
                days = list(dataset)
                days.sort(key=lambda e: levenshtein(day, e))
                return days[0] + day_extraction.group(2)