01_Book.py

def var():

    print("it's a variable")

def str():

    print("it's a string")

def loop():

    print("it's a loop")

def func():

    print("it's a func")

def book():

    print('''learn

    1. var

    2. str

    3. loop

    4. func''')

    page = int(input("Enter page no: "))

    def test(page):

        if page == 1:

            var()

        elif page == 2:

            str()

        elif page == 3:

            loop()

        elif page == 4:

            func()

        else:

            print("choose correctly")

           

        home = input('''go to home (h):

    go to previous page (p):

    go to next page (n):''')

        if home == "h":

            book()

        elif home == "p":

            page = page-1

            test(page)

        elif home == "n":

            page = page+1

            test(page)

        else:

            print("Error")

    test(page)

book()