Bbcode transfer 𝚝𝚑𝚒𝚜 𝚝𝚎𝚡𝚝

import re


def replace_placeholder():
    while True:
        replacement_string = input("\nstring: ")
        code = input("code: ")

        placeholders = list(re.finditer("�", code))
        count = len(placeholders)

        if count % 2 != 0:
            print("Ошибка: число '�' должно быть чётным.")
            continue

        if len(replacement_string) < 2:
            print("error")
            continue

        gradient = replacement_string[1:]

        result = []
        last_index = 0
        counter = 0
        gradient_index = 0

        for match in re.finditer("�", code):
            start, end = match.span()
            result.append(code[last_index:start])
            counter += 1
            if counter % 2 == 1:
                pass
            else:
                if gradient_index < len(gradient):
                    result.append(gradient[gradient_index])
                    gradient_index += 1
            last_index = end
        result.append(code[last_index:])
        new_code = "".join(result)

        new_code = re.sub(r'\[color=#([0-9a-fA-F]{6})\]\s*\[/color\]', '', new_code)

        print("\ndone:")
        print(new_code)


if __name__ == "__main__":
    replace_placeholder()