如何过滤XML文档中的XML节点及其子节点？

import xml.etree.ElementTree as ET

def filter_xml(xml_string, xpath_expression):
    # 解析XML字符串
    root = ET.fromstring(xml_string)
    
    # 使用XPath表达式选择要过滤的节点
    filtered_nodes = root.findall(xpath_expression)
    
    # 移除选中的节点及其子节点
    for node in filtered_nodes:
        root.remove(node)
    
    # 返回过滤后的XML字符串
    return ET.tostring(root, encoding="utf-8").decode()

# 示例XML文档
xml_string = """
<root>
    <node1>Content 1</node1>
    <node2>Content 2</node2>
    <node3>Content 3</node3>
</root>
"""

# XPath表达式，选择要过滤的节点
xpath_expression = "//node2"

# 调用过滤函数
filtered_xml = filter_xml(xml_string, xpath_expression)

# 输出结果
print(filtered_xml)