Как реализовать кнопку 'назад' в телеграм боте?

from telebot import TeleBot, types
from config import TELEGRAM_API_TOKEN
import json

bot = TeleBot(TELEGRAM_API_TOKEN)



@bot.message_handler(commands=['start'])
def search_vanacies(message):
    start_search_keyabord = types.ReplyKeyboardMarkup(
        resize_keyboard=True, row_width=2)
    button = types.KeyboardButton(' Поиск вакансий')
    start_search_keyabord.add(button)
    msg = bot.send_message(message.chat.id, '.',
                           reply_markup=start_search_keyabord)
    bot.register_next_step_handler(msg, city_selector)


def city_selector(message):
    select_city_keyaboard = types.ReplyKeyboardMarkup(
        resize_keyboard=True, row_width=2)
    c = open('cities.json', encoding='utf-8')
    cities = json.load(c)
    pairs = [cities[i:i+2] for i in range(0, len(cities), 2)]
    # print(pairs)
    back = types.KeyboardButton('назад')
    select_city_keyaboard.row(back)
    for i in pairs:
        btn1 = types.KeyboardButton(i[0]['city'])
        btn2 = types.KeyboardButton(i[1]['city'])
        select_city_keyaboard.row(btn1, btn2)
    msg = bot.send_message(message.chat.id, 'Выберете интересующий вас город',
                           reply_markup=select_city_keyaboard)
    bot.register_next_step_handler(msg, region_selector)


def region_selector(message):

    c = open('cities.json', encoding='utf-8')
    cities = json.load(c)
    for r in cities:
        if message.text == r['city']:
            regions = r['regions']
            pairs = [regions[i:i+2] for i in range(0, len(regions), 2)]
            select_region_keyboard = types.ReplyKeyboardMarkup(
                resize_keyboard=True, row_width=2)
            back = types.KeyboardButton(' <- назад')
            select_region_keyboard.row(back)

            for i in pairs:
                try:
                    btn1 = types.KeyboardButton(i[0])
                    btn2 = types.KeyboardButton(i[1])
                    select_region_keyboard.row(btn1, btn2)
                except Exception:
                    btn = types.KeyboardButton(i[0])
                    select_region_keyboard.row(btn1)

            bot.send_message(message.chat.id, 'Теперь выберете район',
                             reply_markup=select_region_keyboard)


if __name__ == '__main__':
    bot.remove_webhook()
    bot.polling()