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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 append(self, event, category=None):
 """ Adds a new event to the trace store. The event may hava a category Args: event (spade.message.Message):
 the event to be stored category (str, optional):
 a category to classify the event (Default value = None) """

        date = datetime.datetime.now()
        self.store.insert(0, (date, event, category))
        if len(self.store) > self.size:
            del self.store[-1]