Class Structure of TKInter Program Discord Question

import tkinter as tk
from Frame_Class import FrameClass

class Base(tk.Frame): #A
    def __init__(self, parent:tk.Tk):
        super(Base, self).__init__(parent) #A
        self.left_frame = LeftFrame(self)
        self.left_frame.grid(row=0, column=0)
        self.right_frame = RightFrame(self)
        self.right_frame.grid(row=0, column=1)
        parent.bind('<<RightButton>>', lambda x: self.do_stuff())
        self.pack() #A

    def do_stuff(self):
        left_value = self.left_frame.entry.get()
        new_value = left_value + self.right_frame.entry.get()
        self.left_frame.label.configure(text=new_value)


class LeftFrame(tk.Frame):
    def __init__(self, parent):
        super(LeftFrame, self).__init__(parent)
        self.label = tk.Label(self, text='foo')
        self.label.pack()
        self.entry = tk.Entry(self)
        self.entry.pack()

class RightFrame(tk.Frame):
    def __init__(self, parent):
        super(RightFrame, self).__init__(parent)
        self.butt_direct = tk.Button(self, command=self.do_stuff, text='direct')
        self.butt_direct.pack()
        self.butt_event = tk.Button(self, command=self.do_stuff_event, text='event')
        self.butt_event.pack()
        self.entry = tk.Entry(self)
        self.entry.pack()

    def do_stuff(self):
        left_value = self.master.left_frame.entry.get()
        new_value = left_value + self.entry.get()
        self.master.left_frame.label.configure(text=new_value)

    def do_stuff_event(self):
        self.event_generate('<<RightButton>>')


def main():
    root = tk.Tk()
    Base(root)
    root.mainloop()

if __name__ == "__main__": main()