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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 _make_indices(self, Ns):
        ''' makes indices for cross validation '''
        N_new = int(Ns * self.n_splits)

        test = [np.full(N_new, False) for i in range(self.n_splits)]
        for i in range(self.n_splits):
            test[i][np.arange(Ns * i, Ns * (i + 1))] = True
        train = [np.logical_not(test[i]) for i in range(self.n_splits)]

        test = [np.arange(N_new)[test[i]] for i in range(self.n_splits)]
        train = [np.arange(N_new)[train[i]] for i in range(self.n_splits)]

        cv = list(zip(train, test))
        return cv