How to pass value to a global variable through a Button command in Tkinter?

Question

I'm a newbie to python. Would you be able to help me find a way to pass a value onto the CommonPage class for the 'mypage' variable, rather than it being hardcoded onto there. I plan for both pages A and B to have the same format and structure, but different values for variables (such as the title as in this example). This is why I would like to use only one class for both pages A and B, rather than two separate classes with similar code but different values for the variables. Is this possible?

thank you! any help would be much appreciated

from tkinter import *
import tkinter.ttk as ttk

class MyApp(Tk):
    def __init__(self):
        Tk.__init__(self)
        container = ttk.Frame(self)
        container.pack(side="top", fill="both", expand=True)
        self.frames = {}
        for F in (HomePage, CommonPage):
            frame = F(container, self)
            self.frames[F] = frame
            frame.grid(row=0, column=0, sticky='NSEW')
        self.show_frame(HomePage)

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

class HomePage(ttk.Frame):
    def __init__(self, parent, controller):
        self.controller = controller
        ttk.Frame.__init__(self, parent)

        # create all of the main containers
        top_frame = Frame(self, bg='blue', width=355, height=50)
        mid_frame = Frame(self, bg='MediumPurple4', width=350, height=50)
        bottom_frame = Frame(self, bg='#a0ccda', width=350, height=100)

        # to go inside top_frame
        titleLabel = Label(top_frame, font=('Arial', 23, 'bold'), text="My App",
                           bd=5, fg='snow',bg='blue', width=19, height=1)
        titleLabel.grid(row=0, column=0, sticky=N)
        top_frame.pack()

        # to go inside mid_frame
        titleLabel = Label(mid_frame, font=('Helvetica', 15, 'italic'), text="",
                           bd=5, fg='snow',bg='black', width=30, height=1)
        titleLabel.grid(row=1, column=0, sticky=N)
        mid_frame.pack()

        # to go inside bottom_frame
        titleLabel = Label(bottom_frame, font=('Helvetica', 15, 'italic'), text="Select Button Page Below", bd=5, fg='snow',bg='gray', width=30)
        titleLabel.grid(row=1, column=0, sticky=N)
        # button to CommonPage
        # need to pass the Page Button selected to the CommonPage class 
        btnPageA = Button(bottom_frame, text="Page A", font="Arial 20",
                          command=lambda: [self.controller.show_frame(CommonPage)], 
                          bg="#a0ccda", width=22)
        btnPageA.grid(row=2, column=0, sticky=W)
        btnPageB = Button(bottom_frame, text="Page B", font="Arial 20",
                          command=lambda: [self.controller.show_frame(CommonPage)],
                          bg="#a0ccda", width=22)
        btnPageB.grid(row=3, column=0, sticky=W)
        bottom_frame.pack()

class CommonPage(ttk.Frame):
    def __init__(self, parent, controller):
        self.controller = controller  
        ttk.Frame.__init__(self, parent)
  
        top_frame = Frame(self, bg='blue', width=355, height=50)
        bottom_frame = Frame(self, bg='#a0ccda', width=350, height=0)
        btnHomePage = ttk.Button(top_frame, text='Home Page',
                                 command=lambda: self.controller.show_frame(HomePage))
        btnHomePage.grid(row=0, sticky=W)
        ## hardcoded as shown, this needs to be passed when a page button is selected
        SelectedPage = "Page B"  
        if SelectedPage == "Page A":
            mypage = "Page A"
        else: 
            mypage = "Page B"
        ##
        
        titleLabel = Label(top_frame, font=('Arial', 23, 'bold'), text=mypage, bd=5, fg='snow',bg='blue', width=19, height=1)
        titleLabel.grid(row=1, column=0, sticky=S)
        top_frame.pack()
        bottom_frame.pack()

if __name__ == '__main__':
    app = MyApp()
    app.title('Mobile App')
    app.geometry('{}x{}'.format(355, 230))