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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 _qmed_from_area(self):
 """ Return QMED estimate based on catchment area. TODO: add source of method :return: QMED in m³/s :rtype: float """

        try:
            return 1.172 * self.catchment.descriptors.dtm_area ** self._area_exponent()  # Area in km²
        except (TypeError, KeyError):
            raise InsufficientDataError("Catchment `descriptors` attribute must be set first.")