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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 OECDas(self, to='name_short'):
 """ Return OECD member states in the specified classification Parameters to : str, optional Output classification (valid str for an index of country_data file), default: name_short Returns ------- Pandas DataFrame """

        if isinstance(to, str):
            to = [to]
        return self.data[self.data.OECD > 0][to]