n1 = bt.make_node()
bt.set_node_data(n1, 1)
n2 = bt.make_node()
bt.set_node_data(n2, 2)
n3 = bt.make_node()
bt.set_node_data(n3, 3)
n4 = bt.make_node()
bt.set_node_data(n4, 4)
n5 = bt.make_node()
bt.set_node_data(n5, 5)
n6 = bt.make_node()
bt.set_node_data(n6, 6)
n7 = bt.make_node()
bt.set_node_data(n7, 7)
bt.set_root(n1)
bt.make_left_sub_tree(n1, n2)
bt.make_right_sub_tree(n1, n3)
bt.make_left_sub_tree(n2, n4)
bt.make_right_sub_tree(n2, n5)
bt.make_left_sub_tree(n3, n6)
bt.make_right_sub_tree(n3, n7)
