cifrario di cesare by lokk3d [GUI]

try:
    from tkinter import *
except:
    from Tkinter import *

def leggifile(nomefile):
        lines = []
        try:
            miofile = open(nomefile)
            miofile.close()
        except FileNotFoundError:
            fatto.grid(column = 0, row = 5,columnspan = 2, padx = 10, pady = 10)
            fatto.configure(text = "File non trovato, file creato")
        else:
            for l in open(nomefile):
                lines.append(l.strip())
            return lines

def scrivifile(nomefile, lista):
        miofile = open(nomefile, "w")
        for cont in lista:
            miofile.writelines(cont + "\n")
        miofile.close()
        fatto.grid(column = 0, row = 5,columnspan = 2, padx = 10, pady = 10)

def codifica(riga, chiave):
    return ''.join([chr(ord(lettera) + chiave) for lettera in riga])

def decodifica(riga, chiave):
    return ''.join([chr(ord(lettera) - chiave) for lettera in riga])

def main():
    linee = leggifile(nomefile.get())
    nuovofile = []
    if scelta.get() == 0:
        for x in linee:
            stringa = codifica(x,int(chiave.get()))
            nuovofile.append(stringa)
    elif scelta.get() == 1:
        for x in linee:
            stringa = decodifica(x, int(chiave.get()))
            nuovofile.append(stringa)
    scrivifile(nomefile.get(), nuovofile)

root = Tk()
root.geometry("350x240")
root.resizable(False, False)
root.title("Cifrario di Cesare")
root.configure(bg = "white")
l1= Label(root,text = "Inserisci il percorso del file:",bg = "white")
nomefile = StringVar(value = "")
e1 = Entry(root, textvariable = nomefile,width= 40,bg = "white")
l2 = Label(root, text = "Inserisci la chiave:",bg = "white")
chiave = StringVar(value = "")
s1 = Spinbox(root, from_= 0,to= 255,width= 10, textvariable = chiave,bg = "white")
scelta = IntVar()
r1 = Radiobutton(root, text = "Cripta", value = 0, variable = scelta,bg = "white")
r2 = Radiobutton(root, text = "Decripta", value = 1,variable = scelta,bg = "white")
bt1 = Button(root, text = "Vai",bg = "white", command = main)
fatto = Label(root, text = "File modificato con successo!!", bg = "white" )

l1.grid(column = 0, row = 0, columnspan = 2, padx = 10, pady = 10)
e1.grid(column = 0, row = 1, columnspan = 2, padx = 10, pady = 10)
l2.grid(column = 0, row = 2, padx = 10, pady = 10)
s1.grid(column = 1, row = 2, padx = 10, pady = 10)
r1.grid(column = 0, row = 3, padx = 10, pady = 10)
r2.grid(column = 1, row = 3, padx = 10, pady = 10)
bt1.grid(column = 0, row = 4,columnspan = 2, padx = 10, pady = 10)
fatto.grid_forget()
root.mainloop()