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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 piola_kirchoff_1(self, def_grad):
 """ calculates the first Piola-Kirchoff stress Args: def_grad (3x3 array-like):
 deformation gradient tensor """

        if not self.is_symmetric:
            raise ValueError("The stress tensor is not symmetric, \
                             PK stress is based on a symmetric stress tensor.")
        def_grad = SquareTensor(def_grad)
        return def_grad.det*np.dot(self, def_grad.inv.trans)