python - 'method' object is not subscriptable -

i'm trying use bryan oakley's solution this question when try edit frames fit purpose error. code is:

import tkinter tk  class sampleapp(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)          self.frames = {}         f in (mainmenu, createpage, viewpage):             page_name = f.__name__             frame = f(parent=container, controller=self)             self.frames[page_name] = frame             frame.grid(row=0, column=0, sticky="nsew")          self.show_frame("mainmenu")      def show_frame(self, page_name):         frame = self.frame[page_name]         frame.tkraise()  class mainmenu(tk.frame):     def __init__(self, parent, controller):         tk.frame.__init__(self, parent)         self.controller = controller         controller.title("main menu")         controller.configure(background="light green")          titlelbl = tk.label(controller,                             text="golf scorecards",                             fg = "dark green",                             font = "verdana 20 bold")          newbtn = tk.button(controller,                            text="create new scorecard",                            fg = "light green",                            bg = "dark green",                             command = lambda: controller.show_frame("createpage"))          viewbtn = tk.button(controller,                             text="view existing scorecard",                              fg = "light green",                             bg = "dark green",                              command = lambda: controller.show_frame("viewpage"))          exitbtn = tk.button(controller,                             text="exit program",                             fg = "light green",                             bg = "dark green",                              command = controller.quit)          titlelbl.pack(side="top", fill="x", pady=10)         newbtn.pack(fill="x", padx=20, pady=30)         viewbtn.pack(fill="x", padx=20, pady=30)         exitbtn.pack(fill="x", padx=20, pady=30)  class createpage(tk.frame):     def __init__(self, parent, controller):         tk.frame.__init__(self, parent)         self.controller = controller          label = tk.label(self,                          text="this create page",                           font = "verdana 20 bold")          button = tk.button(self,                            text="go main menu",                            command = lambda: controller.show_frame("mainmenu"))          label.pack(side="top", fill="x", pady=10)         button.pack()  class viewpage(tk.frame):     def __init__(self, parent, controller):         tk.frame.__init__(self, parent)         self.controller = controller          label = tk.label(self,                          text="this view page",                           font = "verdana 20 bold")          button = tk.button(self,                            text="go main menu",                            command = lambda: controller.show_frame("mainmenu"))          label.pack(side="top", fill="x", pady=10)         button.pack()  if __name__ == "__main__":     app = sampleapp()     app.mainloop() 

sorry if answer obvious, haven't been using tkinter long.

you forgot 's' in show_frame:

replace self.frame[page_name] = frame self.frames[page_name] = frame , code should run.