python基础习题，求解答

def dayUP(df):
    dayup = 1
    for i in range(365):
        if i % 7 in [6,0]:
            dayup = dayup*(1 - 0.01)
        else:
            dayup = dayup*(1 + df)
    return dayup
dayfactor = 0.01
while dayUP(dayfactor) < 37.78:
    dayfactor += 0.001
print("工作日的努力参数是: {:.3f}".format(dayfactor))

if i % 7 in [6,0]:
            dayup = dayup*(1 - 0.01)不懂

i 的取值是0～364，i % 7的意思是i对7取余数；

当值等于0或者6的时候，执行dayup = dayup*(1 - 0.01)，==> dayup的初始值为1，即1 * (1 - 0.01)