Python中pool进程池计算完的结果如何取用分析

import time
import multiprocessing
from numpy import *

def job(x ,y):
    return x * y
def job1(z):
    return job(z[0], z[1])

if __name__ == "__main__":
    pool = multiprocessing.Pool(2)
    data_list=[(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9),(10,10)]
    res = pool.map(job1,data_list)
    time2=time.time()
    print(res)

a = mean(res)
print(a)

第18行的取用res结果报错，有没有可以取用的方法

a = mean(res)
print(a)
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