如何在文件中找到一个单词或行，并将其下面的行替换为一个新单词？

def replace_word_in_file(file_path, target_word, new_word):
    with open(file_path, 'r') as file:
        lines = file.readlines()

    with open(file_path, 'w') as file:
        for i in range(len(lines)):
            line = lines[i]
            if target_word in line:
                if i+1 < len(lines):
                    lines[i+1] = new_word + '\n'
            file.write(line)

file_path = 'example.txt'
target_word = 'apple'
new_word = 'orange'
replace_word_in_file(file_path, target_word, new_word)