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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 train_vine(self, tree_type):
 """Train vine."""

        LOGGER.debug('start building tree : 0')
        tree_1 = Tree(tree_type)
        tree_1.fit(0, self.n_var, self.tau_mat, self.u_matrix)
        self.trees.append(tree_1)
        LOGGER.debug('finish building tree : 0')

        for k in range(1, min(self.n_var - 1, self.truncated)):
            # get constraints from previous tree
            self.trees[k - 1]._get_constraints()
            tau = self.trees[k - 1].get_tau_matrix()
            LOGGER.debug('start building tree: {0}'.format(k))
            tree_k = Tree(tree_type)
            tree_k.fit(k, self.n_var - k, tau, self.trees[k - 1])
            self.trees.append(tree_k)
            LOGGER.debug('finish building tree: {0}'.format(k))