#!/usr/bin/env python3
 
import urllib.request
 
def loadfile(url, fname, bsize=1024, ihook=None):
    data = urllib.request.urlopen(url)
    out = open(fname, 'wb')
    with data, out:
        block = True
        cur_size = 0
        tot_size = int(data.headers['Content-Length'])
        while block:
            block = data.read(bsize)
            out.write(block)
            if ihook is not None:
                blen = len(block)
                if blen > 0:
                    cur_size += blen
                    ihook(cur_size, tot_size)
 
def print_percent(cur, tot):
    print('\r{:d}%'.format(int(100 * cur / tot)), end='')
    if cur == tot:
        print()
 
def main():
    url = 'http://cdn.download.comodo.com' \
          '/av/updates51/sigs/bases/bases.cav'
    ofname = 'bases.cav'
    loadfile(url, ofname, ihook=print_percent)
 
if __name__ == '__main__':
    main()

>>> import dlper
>>> dlper.loadfile('http://www.yandex.ru', 'yandex.html', ihook=lambda c, t: print('Current:', c, 'Total:', t))
Current: 1024 Total: 62280
Current: 2048 Total: 62280
Current: 3072 Total: 62280
Current: 4096 Total: 62280
Current: 5120 Total: 62280
Current: 6144 Total: 62280
Current: 7168 Total: 62280
Current: 8192 Total: 62280
Current: 9216 Total: 62280
Current: 10240 Total: 62280
Current: 11264 Total: 62280
Current: 12288 Total: 62280
Current: 13312 Total: 62280
Current: 14336 Total: 62280
Current: 15360 Total: 62280
Current: 16384 Total: 62280
Current: 17408 Total: 62280
Current: 18432 Total: 62280
Current: 19456 Total: 62280
Current: 20480 Total: 62280
Current: 21504 Total: 62280
Current: 22528 Total: 62280
Current: 23552 Total: 62280
Current: 24576 Total: 62280
Current: 25600 Total: 62280
Current: 26624 Total: 62280
Current: 27648 Total: 62280
Current: 28672 Total: 62280
Current: 29696 Total: 62280
Current: 30720 Total: 62280
Current: 31744 Total: 62280
Current: 32768 Total: 62280
Current: 33792 Total: 62280
Current: 34816 Total: 62280
Current: 35840 Total: 62280
Current: 36864 Total: 62280
Current: 37888 Total: 62280
Current: 38912 Total: 62280
Current: 39936 Total: 62280
Current: 40960 Total: 62280
Current: 41984 Total: 62280
Current: 43008 Total: 62280
Current: 44032 Total: 62280
Current: 45056 Total: 62280
Current: 46080 Total: 62280
Current: 47104 Total: 62280
Current: 48128 Total: 62280
Current: 49152 Total: 62280
Current: 50176 Total: 62280
Current: 51200 Total: 62280
Current: 52224 Total: 62280
Current: 53248 Total: 62280
Current: 54272 Total: 62280
Current: 55296 Total: 62280
Current: 56320 Total: 62280
Current: 57344 Total: 62280
Current: 58368 Total: 62280
Current: 59392 Total: 62280
Current: 60416 Total: 62280
Current: 61440 Total: 62280
Current: 62280 Total: 62280
>>>

from  tkinter import  * 
# создание базового окна 
root =  Tk() 
root.title("Этo я,метка") 
root.geometry("200х50") 
арр = Frame(root)
app.grid() 
lbl = Label(app.text ="Вот она я!") 
lbl=Label(app.tax="ВОТ оня")
root.mainloop()

keyword can not be an expression

lbl = Label(app.text ="Вот она я!")

#!/usr/bin/env python3
 
import tkinter as tk
from tkinter.constants import *
 
class App(tk.Frame):
    def __init__(self, master=None):
        tk.Frame.__init__(self, master)
        self.pack(fill=BOTH)
        self.create_widgets()
 
    def create_widgets(self):
        self.frame_top = tk.Frame(self)
        self.frame_top.pack(fill=BOTH)
        self.frame_bottom = tk.Frame(self)
        self.frame_bottom.pack(fill=BOTH)
         
        self.frame_top.label_enter = tk.Label(self.frame_top, text='Enter:')
        self.frame_top.label_enter.pack(side=LEFT)
 
        self.frame_top.entry_var = tk.StringVar()
        self.frame_top.entry_var.set('???')
        self.frame_top.entry = tk.Entry(self.frame_top, textvariable=self.frame_top.entry_var)
        self.frame_top.entry.pack(side=LEFT)
 
        self.frame_top.button_ok = tk.Button(self.frame_top,
                                             text='Ok',
                                             command=self.press_button_ok)
        self.frame_top.button_ok.pack(side=LEFT)
        self.frame_top.button_quit = tk.Button(self.frame_top,
                                               text='Quit',
                                               command=self.master.destroy)
        self.frame_top.button_quit.pack(side=LEFT)
 
        self.frame_bottom.label_result_info = tk.Label(self.frame_bottom, text='Result:')
        self.frame_bottom.label_result_info.pack(side=LEFT)
 
        self.frame_bottom.label_result_var = tk.StringVar()
        self.frame_bottom.label_result_var.set('***')
        self.frame_bottom.label_result = tk.Label(self.frame_bottom,
                                                  textvariable=self.frame_bottom.label_result_var)
        self.frame_bottom.label_result.pack(side=LEFT)
        
    def press_button_ok(self):
        entry_string = self.frame_top.entry_var.get()
 
        print(repr(entry_string))
        self.frame_bottom.label_result_var.set(entry_string)
 
def main():
    root = App()
    root.master.title('Window')
    root.master.geometry('300x70+500+500')
    root.mainloop()
 
if __name__ == '__main__':
    main()

from tkinter import *
class quitButton(Button):
    def __init__(self, parent):
        Button.__init__(self, parent)
        self['text'] = 'НАЧАТЬ'
        self['command'] = parent.destroy
        self.pack(side=BOTTOM)
root = Tk()
quitButton(root)
mainloop()

from tkinter import *
import os
os.getcwd()
class quitButton(Button):
    def __init__(self, parent):
        Button.__init__(self, parent)
        self['text'] = 'НАЧАТЬ'
        self[os.system('D:\\build\base\script.exe')]=parent.destroy 
        self.pack(side=BOTTOM)
root = Tk()
openfileButton(root)
mainloop()

self[os.system('D:\\build\base\script.exe')]=parent.destroy