pages.py

pages = [x.strip() for x in texts.get('register.start_welcome').split('--break--')]

    if page_id < 0:
        page_id = 0

    if page_id >= len(pages):
        page_id = len(pages) - 1

    if page_id == 0 or from_scratch:
        if page_id != len(pages) - 1:
            button_list = [[InlineKeyboardButton(texts.get('button.next'),
                                                 callback_data='register-button.next-{}'.format(
                                                        page_id + 1
                                                  ))]]
        else:
            button_list = [[]]
    else:
        button_list = [
                        [
                            InlineKeyboardButton(texts.get('button.back'),
                                                 callback_data='register-button.back-{}'.format(
                                                     page_id - 1
                                                 )),
                        ]
                      ]

        if page_id != len(pages) - 1:
            button_list[0].append(InlineKeyboardButton(texts.get('button.next'),
                                                       callback_data='register-button.next-{}'.format(
                                                           page_id + 1
                                                       )))

    if page_id == len(pages) - 1:
        button_list.append([
            InlineKeyboardButton(texts.get('button.register'), callback_data='register-button.register')
        ])

    reply_markup = InlineKeyboardMarkup(button_list)

    if from_scratch:
        update.message.reply_text(pages[0],
                                  reply_markup=ReplyKeyboardRemove(),
                                  parse_mode="Markdown")

        update.message.edit_message_reply_markup(
                                  reply_markup=reply_markup,
                                  parse_mode="Markdown")
    else:
        update.message.edit_text(pages[page_id],
                                 reply_markup=reply_markup,
                                 parse_mode="Markdown")