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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 _get_top_of_rupture_depth_term(self, C, imt, rup):
 """ Compute and return top of rupture depth term. See paragraph 'Depth-to-Top of Rupture Model', page 1042. """

        if rup.ztor >= 20.0:
            return C['a15']
        else:
            return C['a15'] * rup.ztor / 20.0