Why is this opening 2 windows/frames?

[WuchaDoin]

from tkinter import *

class App(Tk):

    def __init__(self, root):

        Tk.__init__(self)

        self.geometry("1280x720")

        MainFrame = Frame(self, width=30, height=40, bg='blue')
        SecFrame = Frame(self, width=30, height=40, bg='red')
        MainFrame.grid(row=0, column=2)
        SecFrame.grid(row=1, column=2)

self = Tk()
App = App(self)
self.mainloop()

Very basic structure, but with something so basic, I cannot figure out why it continues to open 2 windows.

---

Solved it.

self = Tk()
App = App(self)
self.mainloop()

Needed to be changed to:

App = App()
App.mainloop()

to simplify further:

App().mainloop()