how can I write my function output on CSV file

[go127a]

here is my csv code:

mandana,5,7,3,15
hamid,3,9,4,20,9,1,8,16,0,5,2,4,7,2,1
sina,19,10,19,6,8,14,3
sara,0,5,20,14
soheila,13,2,5,1,3,10,12,4,13,17,7,7
ali,1,9
sarvin,0,16,16,13,19,2,17,8

and I am going to calculate the mean of every list in csv and add the name and mean to the csv file.

import csv
from statistics import mean

import csv
from statistics import mean

with open ('grades.csv', 'r') as input_file_name:
    reader=csv.reader(input_file_name)
    lastrow=[]
    for row in reader:
        #print (row)
        name = row[0]
        these_grades=list()
        
        for grade in row[1:]:
            #print(grade)
            these_grades.append(int(grade))
            #print(name,grade,these_grades)
            
        print(name, mean(these_grades))
with open('grades.csv', 'w', newline='') as output_file_name:
    writer = csv.writer(output_file_name)
    writer.writerows(name )
    writer.writerows(mean )