Python Parameter Passing -

i'm working on making modified version of pong college class , having trouble passing methods. believe have set way needs to able parameter passing. code runs fine , stops working after while loop in main function. appreciated.

    import pygame      scr_wid, scr_hei = 640, 480     class player():             def __init__(self):                     self.x, self.y = 16, scr_hei/2                     self.x1, self.y1 = scr_wid-16, scr_hei/2                     self.speed = 3                     self.padwid, self.padhei = 8, 64                     self.score = 0                     self.scorefont = pygame.font.font("imagine_font.ttf", 64)              def scoring(self):                     scoreblit = self.scorefont.render(str(self.score), 1, (0,0,0))                     screen.blit(scoreblit, (32, 16))                     if self.score == 10:                             print ("player 1 wins!")                             exit()              def scoring1(self):                     scoreblit = self.scorefont.render(str(self.score), 1, (0,0,0))                     screen.blit(scoreblit, (scr_hei+92, 16))                     if self.score == 10:                             print ("player 2 wins!")                             exit()              def movement(self):                                      keys = pygame.key.get_pressed()                     if keys[pygame.k_w]:                             self.y -= self.speed                     elif keys[pygame.k_s]:                             self.y += self.speed                      if self.y <= 0:                             self.y = 0                     elif self.y >= scr_hei-64:                             self.y = scr_hei-64                      keys1 = pygame.key.get_pressed()                     if keys1[pygame.k_up]:                             self.y1 -= self.speed                     elif keys1[pygame.k_down]:                             self.y1 += self.speed                      if self.y1 <= 0:                             self.y1 = 0                     elif self.y >= scr_hei-64:                             self.y1 = scr_hei-64              def draw(self):                     pygame.draw.rect(screen, (0,0,0), (self.x, self.y, self.padwid, self.padhei))                     pygame.draw.rect(screen, (0,0,0), (self.x1, self.y1, self.padwid, self.padhei))        class ball():             def __init__(self):                     self.x, self.y = scr_wid/2, scr_hei/2                     self.x1, self.y1 = scr_wid/2, scr_hei/2                     self.speed_x = -3                     self.speed_y = 3                     self.size = 8              def movement(self):                     self.x += self.speed_x                     self.y += self.speed_y                      if self.y <= 0:                             self.speed_y *= -1                     elif self.y >= scr_hei-self.size:                             self.speed_y *= -1                      if self.x <= 0:                             self.__init__()                             enemy.score += 1                     elif self.x >= scr_wid-self.size:                             self.__init__()                             self.speed_x = 3                             player.score += 1                     n in range(-self.size, player.padhei):                             if self.y == player.y + n:                                     if self.x <= player.x + player.padwid:                                             self.speed_x *= -1                                             break                             n += 1                     self.x1 += self.speed_x                     self.y1 += self.speed_y                      if self.y1 <= 0:                             self.speed_y *= -1                     elif self.y1 >= scr_hei-self.size:                             self.speed_y *= -1                      if self.x1 <= 0:                             self.__init__()                             enemy.score += 1                     elif self.x1 >= scr_wid-self.size:                             self.__init__()                             self.speed_x = 3                             player.score += 1                     n in range(-self.size, enemy.padhei):                             if self.y1 == enemy.y1 + n:                                     if self.x1 >= enemy.x1 - enemy.padwid:                                             self.speed_x *= -1                                             break                             n += 1              def draw(self):                     pygame.draw.rect(screen, (112,138,144), (self.x, self.y, 8, 8))      scr_wid, scr_hei = 640, 480     screen = pygame.display.set_mode((scr_wid, scr_hei))     pygame.display.set_caption("justin's pong")     pygame.font.init()     clock = pygame.time.clock()     fps = 60     player = player()      ball = ball()     enemy = player()      def main():         while true:             event in pygame.event.get():                             if event.type == pygame.quit:                                     print ("game exited user")                                     exit()         backgroundimage = pygame.image.load("background.png")         ball.movement()         player.movement()         enemy.movement()         position = (0,0)         screen.fill((0, 0, 0))         screen.blit(backgroundimage, position)         ball.draw()         player.draw()         player.scoring()         enemy.draw()         enemy.scoring1()         pygame.display.flip()         clock.tick(fps)      main() 

nothing beyond while loop executed until loop been completed.

i = 0 while < 5:     print(i)     += 1 print('finished!') 

output:

0 1 2 3 4 finished!