def main():
"""Driver function for a binary search tree."""
bst = BinarySearchTree()
data = [21, 26, 30, 9, 4, 14, 28, 18, 15, 10, 2, 3, 7]
# data = [25, 50, 57, 100, 125, 150, 200]
for i in data:
bst.add(i)
print('21, 9, 4, 2, 3, 7, 14, 10, 18, 15, 26, 30, 28,')
bst.preorder()
print(bst)
# data2 = [21,9,4,18,15,7]
# for i in data2:
# bst.remove(i)
# bst.preorder()
# print(bst)
print('inorder: ', bst.inorder())
print('Height: ', bst.height())
print('Length: ', bst.__len__())
bst.remove(14)
bst.remove(7)
bst.remove(9)
print(bst.rebalance_tree())
print('Height: ', bst.height())
# bst.display()
print('-=-=-')
bst._is_balanced()
print('------')