Tkinter ile Faiz hesaplama

from tkinter import *

class FZ(object):

    def __init__(self):
        self.pen = pencere
        self.pen.title('Faiz Hesaplam Programı')
        self.pen.tk_setPalette("yellowgreen")
        yukseklik = self.pen.winfo_screenheight()
        genislik = self.pen.winfo_screenwidth()

        print("Ekranın yüksekliği:",yukseklik, "\nEkranın genişliği:", genislik)
        self.pen.geometry("320x260+%d+%d"%((genislik-320)/2, (yukseklik-260)/2))
        self.pen.resizable(width=FALSE, height=FALSE)

        frame = LabelFrame(text='Bilgileri girin'.center(27, '-'), font="Verdana 12")
        frame.grid(row=0, column=0, padx=45, pady=8)

        Label(frame, text='Anapara :', font="Verdana 12").grid(row=1, column=0, sticky=W)
        self.anapara = Entry(frame, width=10, font="Verdana 12 bold", justify=CENTER, bg="yellow")
        self.anapara.grid(row=1, column=2, padx=10, pady=8)

        Label(frame, text='Faiz oranı:', font="Verdana 12").grid(row=2, column=0, sticky=W)
        self.oran = Entry(frame, width=10, font="Verdana 12 bold", justify=CENTER, bg="yellow")
        self.oran.grid(row=2, column=2, padx=10, pady=8)

        Label(frame, text='Yıl:', font="Verdana 12").grid(row=3, column=0, sticky=W)
        self.yil = Entry(frame, width=10, font="Verdana 12 bold", justify=CENTER, bg="yellow")
        self.yil.grid(row=3, column=2, padx=10, pady=10)

        self.vki = IntVar()

        Button(text='Hesapla', font="Verdana 12", height=1,
               command=self.hesapla).grid(row=1, column=0)

        self.message = Label(text='..............', fg='yellow', bg='black', font="Verdana 12")
        self.message.grid(row=4, column=0,padx=30, pady=10)

    def hesapla(self):
        while True:
            self.anapara = int(self.anapara.get())
            self.oran = int(self.oran.get())
            self.yil = int(self.yil.get())
            basit_faiz = (self.anapara*self.oran*self.yil)/100


            if self.anapara != 0 and self.oran != 0 and self.oran != 0:
                self.message["text"] = "%.0f Yıllık Faiz Miktarı: %.1fTL \n%.0f Yıllık Toplam para: %sTL"%(self.yil, basit_faiz, self.yil, (self.anapara+basit_faiz))

            elif self.anapara == ('') and self.oran == ('') and self.oran == (''):
                self.message["text"] = "Anapara , faiz oranı veya \n yıl girmediniz."
            else:
                self.message["text"] = "Anapara , faiz oranı veya \n yıl girmediniz."
            return ()
if __name__ == '__main__':
    pencere = Tk()
    uygulama = FZ()
    pencere.mainloop()