如何计算python中BST的高度

我创建了一个BST.现在我想找到BST开发的高度.

这是我构建BST的代码

class Node:
    '''represents a new node in the BST'''
    def __init__(self,key):
        self.key=key
        self.disconnect()
    def disconnect(self):
        self.left=None;
        self.right=None;
        self.parent=None;
    def __str__(self):
        return 'node with kay %s'%self.key

class BST:
    def __init__(self):
        self.root=None

    def insert(self,t):
        '''inserts a new element into the tree'''
        if self.root is None:
            self.root = Node(t)
        else:
            self._do_insert(self.root,t)

    def _do_insert(self,parent,t):
        if t > parent.key:
            if parent.left is None:
                parent.left = Node(t)
            else:
                self._do_insert(parent.left,t)
        elif t < parent.key:
            if parent.right is None:
                parent.right = Node(t)
            else:
                self._do_insert(parent.right,t)
        else:
            # raise a KeyError or something appropriate?
            pass

我有一个数字列表([2,4,6,3,190,1,56 and so on]),通过它可以构建这个BST.

现在我想找到创建的BST的高度.我怎样才能做到这一点？

编辑

根据提供的解决方案,我试过这个: -

def create_bst(values):

    '''Creates a BST and returns the BST created object'''
    BSTobj = BST()

    for i in values:
        BSTobj.insert(i)

    return BSTobj


def height_of_BST(bst):

    '''Returns the height of the BST created'''
    if bst == None: return 0
    else: return 1 + max(height_of_BST(bst.left), height_of_BST(bst.right))


print height_of_BST(create_bst(unique_values))

它不起作用.它弹出一个错误说BST instance has no attribute 'left'