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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 available_labels(self):
 """ Returns the list of classification labels for which we have any explanations. """

        try:
            assert self.mode == "classification"
        except AssertionError:
            raise NotImplementedError('Not supported for regression explanations.')
        else:
            ans = self.top_labels if self.top_labels else self.local_exp.keys()
            return list(ans)