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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 equivalent_crust_cohesion(self):
 """ Calculate the equivalent crust cohesion strength according to Karamitros et al. 2013 sett, pg 8 eq. 14 :return: equivalent cohesion [Pa] """

        deprecation("Will be moved to a function")
        if len(self.layers) > 1:
            crust = self.layer(0)
            crust_phi_r = np.radians(crust.phi)
            equivalent_cohesion = crust.cohesion + crust.k_0 * self.crust_effective_unit_weight * \
                                                    self.layer_depth(1) / 2 * np.tan(crust_phi_r)
            return equivalent_cohesion