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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_wallace_tensor(self, tau):
 """ Gets the Wallace Tensor for determining yield strength criteria. Args: tau (3x3 array-like):
 stress at which to evaluate the wallace tensor """

        b = 0.5 * (np.einsum("ml,kn->klmn", tau, np.eye(3)) +
                   np.einsum("km,ln->klmn", tau, np.eye(3)) +
                   np.einsum("nl,km->klmn", tau, np.eye(3)) +
                   np.einsum("kn,lm->klmn", tau, np.eye(3)) +
                   -2*np.einsum("kl,mn->klmn", tau, np.eye(3)))
        strain = self.get_strain_from_stress(tau)
        b += self.get_effective_ecs(strain)
        return b