Exit function from nested function based on user input

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Hello,

Currently making a chat bot that helps with adding some items to a database. I want a user to be able to start adding something to a database but be able to cancel at anytime.

Here's my current code:

def foo():
    def check(m):
        if m == "stop":
            return

    msg = input("Type a msg: ")
    check(msg)

    msg2 = input("Type another message: ")
    check(msg2)

    msg3 = input("Type a third message: ")

foo()

My thought process was to take the message and run it through a check that would exit out of the process however my check only exists out of the check() function and not the parent foo() function.

I found this thread which is a similar question to mine however I'm not sure exactly how to go about implementing that if it's the same solution.