Credit Card Validator Using Luhn algorithm

 try:

def isluhn(cardNo):

dig=len(cardNo)

nsum=0

isSecond=False

for x in range(dig-1,-1,-1):

d=ord(cardNo[x])-ord('0')

if isSecond==True:

d*=2

nsum+=d//10

nsum+=d%10

isSecond=not isSecond

if  not nsum%10:

return True

return False

card=input("enter card no:")

if (isluhn(card)):

print("This is a valid card")

else:

print("This is not a valid card")

except Exception as e:

print(e)