yield函数

import  re
import  pdb
def yield_test(n):
    for i in range(n):
        yield call(i)
        print("step_3:i=%d\n"%i)
    print("do something else..")
    print("end."

def call(i):
    print("step_1: input %d and call() returns %d"%(i,i*2))
    return i*2

for result in yield_test(5):
    print("step_2:result = %d"%(result))

https://www.cnblogs.com/ethancui/p/5656757.html
这个实践收获很不错，特别爽，人家写的也好。