    def __str__(self):
        if self.time is not None:
            date = datetime.datetime.fromtimestamp(self.time)
            if date.date() == datetime.date.today():
                string_date = 'today'
            elif date.date() == (datetime.date.today() -
                                 datetime.timedelta(1)):
                string_date = 'yesterday'
            elif date.year == datetime.date.today().year:
                string_date = date.strftime('%b %d')
            else:
                string_date = date.strftime('%d %b, %Y')
            string_time = date.strftime('%H:%M:%S')
            string_time = '%s %s ' % (string_date, string_time)
            return self.description + ' - ' + string_time
        return self.description