class Login_window():
    def __init__(self,window):
        self.window = window
        self.window.title("Login")

        top_frame = LabelFrame(self.window)
        top_frame.grid(row=0,column=0)

        mid_frame = LabelFrame(self.window)
        mid_frame.grid(row=2,column=0)

        bottom_frame= LabelFrame(self.window)
        bottom_frame.grid(row=3,column=0)
        Label(top_frame,text = "Enter username:").grid(row=1,column=0)
        self.username_entry = Entry(top_frame)
        self.username_entry.grid(row = 1, column = 1)

        Label(mid_frame,text = "Enter password:").grid(row=3,column=0)
        self.password_entry = Entry(mid_frame)
        self.password_entry.grid(row = 3,column = 3)

        ttk.Button(bottom_frame , text = 'Enter',command = self.returN).grid(row=4,column=0)

def returN(self):
    username=self.username_entry.get()
    password=self.password_entry.get()
    return username,password


def start():
    window=Tk()
    username,password=Login_window(window)
    return username,password
    window.mainloop()