python csv写入数据，消除空行

import csv

rowlist=[{'first_name': 'mark', 'last_name': 'zhao','age':21},

             {'first_name': 'tony', 'last_name': 'wang','age':22},

            {'first_name': 'hengry', 'last_name': 'zhang','age':23},]

#newline设置为空

with open('names.csv', 'w',newline='') as csvfile:

       #构造三个列    

       col_names = ['first_name', 'last_name','age']    

       writer = csv.DictWriter(csvfile, col_names)

       #从头部开始按行写入数据

       writer.writeheader()

       writer.writerows(rowlist)

print(".......................writer over............")