Why didn't Python stop the code, when 'return' statement appeared?

While I was reading this code:

def factorial(number):
    if not isinstance(number, int):
        raise TypeError("Sorry. 'number' must be an integer.")
    if number < 0:
        raise ValueError("Sorry. 'number' must be zero or positive.")
    
    def inner_factorial(number):
        if number <= 1:
            return 1
        return number * inner_factorial(number - 1)
    return inner_factorial(number)

I couldn't understand this part of the code:

    def inner_factorial(number):
        if number <= 1:
            return 1
        return number * inner_factorial(number - 1)
    return inner_factorial(number)

I mean, doesn't Python stop the code, when it sees the statement return? I want to know how the return number * inner_factorial(number - 1) code line works.

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