def is_valid_ID():
    # prompts for input from user
    ID = input("pls type all 9 digits (left to right) of your ID: ")
    assert len(ID)==9
    if control_digit(ID[:-1]) == ID[-1]:
        print("Valid ID number")
    else:
        print("ID number is incorrect")


def control_digit(ID):
    """ compute the check digit in an Israeli ID number """

    total = 0              
    for i in range(8):
        val = int(ID[i])# converts a char to its numeric integer value
        if i%2==0:
            total = total+val
        else:
            if val<5:
                total += 2*val
            else:
                total += (2*val % 10) + 1 # sum of digits in 2*val
    total = total % 10
    check_digit= (10 - total) % 10  # the complement mod 10 of sum

    return str(check_digit)