luhn's solution

cardno=[3,7,1,4,4,9,6,3,5,3,9,8,4,3,1]
sum_1=[]
sum_2=[]
for i in range(len(cardno)):
    if i%2!=0:
        multiby2=cardno[i]*2
        if multiby2<10:
            sum_1.append" rel="noopener" data-mce-href="sum_1.append">sum_1.append" rel="noopener" data-mce-href="sum_1.append">sum_1.append(multiby2)
        else:
            tens=multiby2//10
            ones=multiby2%10
            sum_1.append(tens)
            sum_1.append(ones) 
        
    else:
        sum_2.append(cardno[i])

print(sum_1)
print(sum_2)
sum_3=sum_1+sum_2
sum_t=sum(sum_3)

print(sum_t)
if sum_t%10==0:
   print('valid')  
else:
    print('not')