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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 timeinfo(self):
 """Time series data of the time step. Set to None if no time series data is available for this time step. """

        if self.istep not in self.sdat.tseries.index:
            return None
        return self.sdat.tseries.loc[self.istep]