Number System Conversion

# consts
BASES = [2, 8, 10, 16];

def convert(num, base):
    # create a list to store the converted number
    converted_num = [];
    # create a list to store the digits
    digits = "0123456789ABCDEF";
    # convert the number to the base
    while num > 0:
        converted_num.append(digits[num % base]);
        num = num // base;
    # reverse the list
    converted_num.reverse();
    # join the list
    return "".join(converted_num);

# check if any number is in binary form in a function
def check_valid_form(num, base):

    # create a list to store the digits
    digits = "01";

    if base == 8:
        digits = "01234567";
    elif base == 10:
        digits = "0123456789";
    elif base == 16:
        digits = "0123456789ABCDEF";

    # check the number to the base
    for digit in str(num):
        if digit not in digits:
            return False;
    return True;

nums = [];
bases = [];
total_nums = 0;

# continue taking inputs until the user enters "Stop"
while True:

    # get the number and the base with space to convert
    num_base = input("Enter a number and a base to convert it to decimal (or 'Stop' to quit): \n");

    # if the user enters "Stop"
    if num_base.lower() == "stop":
        break;

    num_base_map = num_base.split();

    if len(num_base_map) == 0:
        print("\nInvalid input\n");
        continue;
    elif len(num_base_map) == 1:
        print("\nInvalid base\n");
        continue;

    nums.append(num_base_map[0]);
    bases.append(num_base_map[1]);
    total_nums += 1;

# check if the base is valid
for i in range(total_nums):

    input_num = int(nums[i]);
    input_base = int(bases[i]);

    print("\nFor number {0} with base {1}:\n".format(input_num, input_base));

    if not input_base or input_base not in BASES or not check_valid_form(input_num, input_base):
        print("Invalid base: " + str(input_base));
        continue;

    for base in BASES:

        if base == input_base:
            continue;

        print(str(convert(input_num, base)) + " if base is " + str(base));