[Flask] Extremely lost on how I am suppose to run a function in Flask views

Bare with me, as I'm new to Flask and this is my first project with it and I have no idea how to even word this or what exactly I need help with.

I have file secp2.py with this function:

def addOne():
    while True:
        choice = input("Would you like to add an item to your lists? ")
        choice = choice.lower()
        if "yes" in choice:
            while True:
                choice = input("Would you like to add a unit or post? ")
                choice = choice.lower()
                if "unit" in choice:
                    posts = SecP(None, employee, None)
                    posts.addAnother()
                    break
                elif "post" in choice:
                    posts = SecP(None, location, None)
                    posts.addAnother()
                    break
                else:
                    print("That's not an option.")
        elif "no" in choice:
            break
        else:
            print("That's not an option.")

As you can see I'm also trying to pass some user input to 2 seperate lists.

I am trying to call/run it in this function from my views.py file:

@app.route('/')
def index():
    return render_template('index.html')

And get it to run with the html template. I have no idea what to do. Am I suppose to rewrite the whole addOne() function in the index() function?