如何将具有不同键的字典列表保存为同一行的csv？

import csv

data = [
    {'Name': 'Alice', 'Age': 25, 'Country': 'USA'},
    {'Name': 'Bob', 'Age': 30, 'Country': 'Canada'},
    {'Name': 'Charlie', 'Age': 35, 'Country': 'UK'}
]

keys = set().union(*data)

with open('output.csv', 'w', newline='') as file:
    writer = csv.DictWriter(file, fieldnames=keys)
    writer.writeheader()
    writer.writerows(data)