python 二叉排序树

class BSTNode:

    def __init__(self, data, left=None, right=None):
  
        self.data = data
        self.left = left
        self.right = right
 
 
class BinarySortTree:
  
    def __init__(self):
        self._root = None
 
    def is_empty(self):
        return self._root is None
 
    def search(self, key):
      
        bt = self._root
        while bt:
            entry = bt.data
            if key < entry:
                bt = bt.left
            elif key > entry:
                bt = bt.right
            else:
                return entry
        return None
 
    def insert(self, key):
    
        bt = self._root
        if not bt:
            self._root = BSTNode(key)
            return
        while True:
            entry = bt.data
            if key < entry:
                if bt.left is None:
                    bt.left = BSTNode(key)
                    return
                bt = bt.left
            elif key > entry:
                if bt.right is None:
                    bt.right = BSTNode(key)
                    return
                bt = bt.right
            else:
                bt.data = key
                return
 
    def delete(self, key):
     
        p, q = None, self._root   
        if not q:
            print("empty tree")
            return
        while q and q.data != key:
            p = q
            if key < q.data:
                q = q.left
            else:
                q = q.right
            if not q:             
                return
    
        if not q.left:
            if p is None:
                self._root = q.right
            elif q is p.left:
                p.left = q.right
            else:
                p.right = q.right
            return

        r = q.left
        while r.right:
            r = r.right
        r.right = q.right
        if p is None:
            self._root = q.left
        elif p.left is q:
            p.left = q.left
        else:
            p.right = q.left
 
    def __iter__(self):
  
        stack = []
        node = self._root
        while node or stack:
            while node:
                stack.append(node)
                node = node.left
            node = stack.pop()
            yield node.data
            node = node.right
 
 

lis = [62, 58, 88, 48, 73, 99, 35, 51, 93, 29, 37, 49, 56, 36, 50]
bs_tree = BinarySortTree()
for i in range(len(lis)):
	bs_tree.insert(lis[i])
# bs_tree.insert(100)
bs_tree.delete(58)
for i in bs_tree:
	print(i, end=" ")
# print("
", bs_tree.search(4))