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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 get_crime_categories(self, date=None):
 """ Get a list of crime categories, valid for a particular date. Uses the crime-categories_ API call. .. _crime-categories: https://data.police.uk/docs/method/crime-categories/ :rtype: list :param date: The date of the crime categories to get. :type date: str or None :return: A ``list`` of crime categories which are valid at the specified date (or at the latest date, if ``None``). """


        return sorted(self._get_crime_categories(date=date).values(),
                      key=lambda c: c.name)