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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 calculate_stress(self, strain):
 """ Calculate's a given elastic tensor's contribution to the stress using Einstein summation Args: strain (3x3 array-like):
 matrix corresponding to strain """

        strain = np.array(strain)
        if strain.shape == (6,):
            strain = Strain.from_voigt(strain)
        assert strain.shape == (3, 3), "Strain must be 3x3 or voigt-notation"
        stress_matrix = self.einsum_sequence([strain]*(self.order - 1)) \
                / factorial(self.order - 1)
        return Stress(stress_matrix)