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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 d_operator(self, P):
 r""" The D operator, mapping P into .. math:: D(P) := P + PC(\theta I - C'PC)^{-1} C'P. Parameters P : array_like(float, ndim=2) A matrix that should be n x n Returns ------- dP : array_like(float, ndim=2) The matrix P after applying the D operator """

        C, theta = self.C, self.theta
        I = np.identity(self.j)
        S1 = dot(P, C)
        S2 = dot(C.T, S1)

        dP = P + dot(S1, solve(theta * I - S2, S1.T))

        return dP