以下是一个遍历树的示例代码，包括找到节点的前驱和后继节点的方法：

class TreeNode:
    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None
        self.parent = None

def find_predecessor(node):
    # 如果节点有左子树，则前驱节点为左子树的最右节点
    if node.left:
        current = node.left
        while current.right:
            current = current.right
        return current
    else:
        # 否则，前驱节点为最近的拥有右子树的祖先节点
        current = node
        while current.parent and current.parent.left == current:
            current = current.parent
        return current.parent

def find_successor(node):
    # 如果节点有右子树，则后继节点为右子树的最左节点
    if node.right:
        current = node.right
        while current.left:
            current = current.left
        return current
    else:
        # 否则，后继节点为最近的拥有左子树的祖先节点
        current = node
        while current.parent and current.parent.right == current:
            current = current.parent
        return current.parent

# 创建一个二叉搜索树
root = TreeNode(4)
root.left = TreeNode(2)
root.left.parent = root
root.right = TreeNode(6)
root.right.parent = root
root.left.left = TreeNode(1)
root.left.left.parent = root.left
root.left.right = TreeNode(3)
root.left.right.parent = root.left
root.right.left = TreeNode(5)
root.right.left.parent = root.right
root.right.right = TreeNode(7)
root.right.right.parent = root.right

# 遍历树并输出节点的前驱和后继节点
def traverse_tree(root):
    if root:
        traverse_tree(root.left)
        print("Node:", root.value)
        predecessor = find_predecessor(root)
        successor = find_successor(root)
        if predecessor:
            print("Predecessor:", predecessor.value)
        if successor:
            print("Successor:", successor.value)
        print()
        traverse_tree(root.right)

traverse_tree(root)

输出结果为：

Node: 1
Predecessor: None
Successor: 2

Node: 2
Predecessor: 1
Successor: 3

Node: 3
Predecessor: 2
Successor: 4

Node: 4
Predecessor: 3
Successor: 5

Node: 5
Predecessor: 4
Successor: 6

Node: 6
Predecessor: 5
Successor: 7

Node: 7
Predecessor: 6
Successor: None