为什么在此代码中使用else语句会导致错误？

Question

在for循环开始的else语句之后，它使语法始终无效

    for i in range(0,15,2):
                          ^
SyntaxError: invalid syntax 

我更改了for循环，并在else语句后更改了该错误

from cs50 import get_string
inp = get_string("Number: \n")
out = "INVALID"
state = ""
sum = 0
if len(inp) == 15:
    state="AMEX"
    for i in range(1, 15, 2):
        if (int(inp[i]) * 2) > 9 :
            sum += (int(inp[i]) * 2) % 10
            sum += (int(inp[i]) * 2) // 10
        else:
            sum = sum + (int(inp[i]) * 2
    for i in range(0,15,2):
        sum += int(inp[i])
        if sum % 10 == 0:
            out = state
            print(out)
        else:
            print(out)