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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 c2r(self):
 """Get real matrix from complex one suitable for solving complex linear system with real solver. For matrix :math:`M(i_1,j_1,\\ldots,i_d,j_d) = \\Re M + i\\Im M` returns (d+1)-dimensional matrix :math:`\\tilde{M}(i_1,j_1,\\ldots,i_d,j_d,i_{d+1},j_{d+1})` of form :math:`\\begin{bmatrix}\\Re M & -\\Im M \\\\ \\Im M & \\Re M \\end{bmatrix}`. This function is useful for solving complex linear system :math:`\\mathcal{A}X = B` with real solver by transforming it into .. math:: \\begin{bmatrix}\\Re\\mathcal{A} & -\\Im\\mathcal{A} \\\\ \\Im\\mathcal{A} & \\Re\\mathcal{A} \\end{bmatrix} \\begin{bmatrix}\\Re X \\\\ \\Im X\\end{bmatrix} = \\begin{bmatrix}\\Re B \\\\ \\Im B\\end{bmatrix}. """

        return matrix(a=self.tt.__complex_op('M'), n=_np.concatenate(
            (self.n, [2])), m=_np.concatenate((self.m, [2])))