Adding Menuing to an existing Example for Tkinter

twoframes.py

# modified from https://pythonprogramming.net/change-show-new-frame-tkinter/
# The code for changing pages was derived from: http://stackoverflow.com/questions/7546050/switch-between-two-frames-in-tkinter
# License: http://creativecommons.org/licenses/by-sa/3.0/

import tkinter as tk

LARGE_FONT = ("Verdana", 12)


class SeaofBTCapp(tk.Tk):

    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        container = tk.Frame(self)

        container.pack(side="top", fill="both", expand=True)

        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)
        
        # New Menu Code Here
        # create a toplevel menu
        menubar = tk.Menu(self)
        menubar.add_command(label="Show Frame 1", command=self.hello)
        menubar.add_command(label="Show Frame 2", command=self.hello2)
        menubar.add_command(label="Quit!", command=self.quit)
        # display the menu
        self.config(menu=menubar)

        self.frames = {}

        for F in (StartPage, PageOne, PageTwo):
            frame = F(container, self)

            self.frames[F] = frame

            frame.grid(row=0, column=0, sticky="nsew")

        self.show_frame(StartPage)

    def show_frame(self, cont):
        frame = self.frames[cont]
        frame.tkraise()

    def hello(self):
        print("Showing Frame 1")
        frame = self.show_frame(PageOne)
        frame.tkraise()
    def hello2(self):
        print("Showing Frame 2")
        frame = self.show_frame(PageTwo)
        frame.tkraise()
        
class StartPage(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        label = tk.Label(self, text="Start Page", font=LARGE_FONT)
        label.pack(pady=10, padx=10)

        button = tk.Button(self, text="Visit Page 1",
                           command=lambda: controller.show_frame(PageOne))
        button.pack()

        button2 = tk.Button(self, text="Visit Page 2",
                            command=lambda: controller.show_frame(PageTwo))
        button2.pack()


class PageOne(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        label = tk.Label(self, text="Page One!!!", font=LARGE_FONT)
        label.pack(pady=10, padx=10)

        button1 = tk.Button(self, text="Back to Home",
                            command=lambda: controller.show_frame(StartPage))
        button1.pack()

        button2 = tk.Button(self, text="Page Two",
                            command=lambda: controller.show_frame(PageTwo))
        button2.pack()


class PageTwo(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        label = tk.Label(self, text="Page Two!!!", font=LARGE_FONT)
        label.pack(pady=10, padx=10)

        button1 = tk.Button(self, text="Back to Home",
                            command=lambda: controller.show_frame(StartPage))
        button1.pack()

        button2 = tk.Button(self, text="Page One",
                            command=lambda: controller.show_frame(PageOne))
        button2.pack()


app = SeaofBTCapp()
app.mainloop()

I modified an existing example I found (see first line) to allow the menu items to choose among frames.