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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 season(self):
 """ Return the current observing season. For *K2*, this is the observing campaign, while for *Kepler*, it is the current quarter. """

        try:
            self._season
        except AttributeError:
            self._season = self._mission.Season(self.ID)
            if hasattr(self._season, '__len__'):
                raise AttributeError(
                    "Please choose a campaign/season for this target: %s." %
                    self._season)
        return self._season