如何将字符附加到字符串第一行的末尾？

def append_to_first_line(string, character):
    lines = string.split('\n')  # 拆分字符串为多行
    lines[0] += character  # 将字符附加到第一行的末尾
    result = '\n'.join(lines)  # 合并字符串数组为一个字符串
    return result

# 示例用法
string = "This is the first line.\nThis is the second line.\nThis is the third line."
character = " (appended)"
result = append_to_first_line(string, character)
print(result)

This is the first line. (appended)
This is the second line.
This is the third line.