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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 _swap_rows(self, i, j):
 """Swap i and j rows As the side effect, determinant flips. """


        L = np.eye(3, dtype='intc')
        L[i, i] = 0
        L[j, j] = 0
        L[i, j] = 1
        L[j, i] = 1
        self._L.append(L.copy())
        self._A = np.dot(L, self._A)