How to register checking and waiting for the correct telebot input?

Question

API

Tell me, please, how to register the correctness check and the expectation of the correct input

Source code:

def question3(message):
    question2 = message.text
    sql.execute(f"""UPDATE users SET answer2 = '{question2}' WHERE user_id = {message.chat.id}""")
...
    bot.register_next_step_handler(msg, question4)

The check should be that the first character is a tag: I tried both through the usual if else, and through while true As a result, either the error message is cycled and sent in a row, or break is triggered for the entire step and the following messages are not sent
question2[0] == '#'

Answer 1

def question3(message):
    user_id = message.chat.id
    question3 = message.text
    if question3.startswith('#'):
        sql.execute("")
        msg = bot.send_message(user_id, 'Отлично! Следующий вопрос...')
        bot.register_next_step_handler(msg, question4)
    else:
        bot.send_message(user_id, 'Ошибка! Введите ещё раз!')
        bot.register_next_step_handler(msg, question3)

Don't use f-strings in SQL queries! Read about SQL injection.