Why did the window in pygame in python begin to close the previous window at startup?

Question

pygame

how to make it so that each new launch of the pygame application closes the previous window. I thought that there was no such possibility and was sad.
Now, against the backdrop of events, I decided to digress, try to repeat what I did from the book, from memory. And for the first time ever, I encountered the closing of a new window of the previous one. No idea what I wrote. Experimentally found out that this is affected by the print function at the beginning of the method. I don't understand how it works. It is worth deleting or commenting it out and the new window no longer closes the previous one.

If anything, the code itself:

# main file

import pygame as pg
from pygame.sprite import Group
from settings import Settings
from ship import Ship
from alien import Alien
import engine

def start():

  settings = Settings()
  pg.init()
  screen = pg.display.set_mode((settings.SCREEN_WIDTH, settings.SCREEN_HEIGHT))

  ship = Ship(screen, settings)
  alien = Alien(screen, settings) 
  bullets = Group()

  while True:
    engine.check_all_events(screen, settings, ship, bullets)
    engine.update_screen(screen, settings, ship, bullets, alien)
    engine.update_bullets(bullets)

start()

(Do not kick for the code. Everything is in the process of remembering and learning.)

import pygame as pg
from pygame.sprite import Group

class Alien():

  def __init__(self, screen, settings):

    self.screen 		= screen
    self.screen_rect 		= self.screen
  
    self.image 			= pg.image.load('img/alien.png')
    self.rect 			= self.image.get_rect()
  
    self.start_pos_X		= self.rect.width
    self.start_pos_Y		= self.rect.height

    self.aliens_amount_X	= round(int((settings.SCREEN_WIDTH / self.rect.width) / 2))

  def draw_alien(self):
    print(self.aliens_amount_X)

    for alien in range(self.aliens_amount_X):

      self.rect.x	 = self.start_pos_X
      self.rect.y	 = self.start_pos_Y

      self.screen.blit(self.image, self.rect)

# The whole point is this print

def draw_alien(self):
    print(self.aliens_amount_X)

How? Why? It doesn't matter what will print, even if print('no_war')