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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 _l_skew_weight(self, donor_catchment):
 """ Return L-SKEW weighting for donor catchment. Methodology source: Science Report SC050050, eqn. 6.19 and 6.22b """

        try:
            dist = donor_catchment.similarity_dist
        except AttributeError:
            dist = self._similarity_distance(self.catchment, donor_catchment)
        b = 0.0219 * (1 - exp(-dist / 0.2360))
        c = 0.2743 / (donor_catchment.record_length - 2)
        return 1 / (b + c)