How to prompt the user for a message in response?

Question

Python

how to use vk_api to make the bot ask the user for a message in response. A person clicks on the "Add products" button, he receives a response so that he writes a list of his products, then you need to do something so that the user enters a list separated by commas and this list was saved into a variable, which I will refer to with other functions, because I will often need to work with it

Answer 1

What prevents to use check on messages?
If there is no message return reply('Specify messages or whatever you need there')
if there is a message break