Python使用CSV模块，当写入多行时，行与行中间出现空行解决办法

这个写法会出现空行问题
import csv

with open("2.csv", "w") as f:
    w = csv.writer(f)
    w.writerow(["1", "2", "3"])
    w.writerow(["4", "5", "6"])

换成这种写法可避免

import csv

with open("3.csv", "w", newline="") as f:
    w = csv.writer(f)
    w.writerow(["1", "2", "3"])
    w.writerow(["4", "5", "6"])