how do I print the inner_inner_func_2 in case without changing the code?

Question

def outer_function(): # this is the outer most function
    print("I am outer")

    def inner_func(): # inner function
        print("I am inner")

        def inner_inner_func(): # inside the inner function
            print("I m inner inner")

            def inner_inner_func_2(): #inside the child of inner child
                print("I a inner inner 2")

            return inner_inner_func_2

        return inner_inner_func

    return inner_func

a = outer_function()

Answer 1

inner functions don't return anything at all; because of it, you don't need to use the return command.
you can just call them with this code:
inner_func_2()

but if your code is something else and bigger that returns something; please edit and fix your question.

Answer 2

There is an formatting mistake in the question, the outer_function was not included.

def outer_function():
    def inner_func(): # inner function
        print("I am inner")
        def inner_inner_func(): # inside the inner fucntion
            print("I m inner inner")
            def inner_inner_func_2(): #inside the child of inner child
                print("I a inner inner 2")
            return inner_inner_func_2
        return inner_inner_func
    return inner_func

outer_function()()()()