import pygame
from pygame.locals import *
pygame.init()
import sys
clock = pygame.time.Clock()
 
myscreen = pygame.display.set_mode((640,480))
myscreen.fill((255,255,255))
 
x, y = (640/2, 480/2)
pygame.key.set_repeat(10, 40)
while 1:
    pygame.display.flip()
    clock.tick(50)
    for event in pygame.event.get():
        if event.type == KEYDOWN: # is a key pressed (down)?
            if event.key == K_ESCAPE: # esc key pressed? exit if so
                sys.exit()
 
            if event.key == K_UP:
                y -= 1
            if event.key == K_DOWN:
                y += 1
            if event.key == K_LEFT:
                x -= 1
            if event.key == K_RIGHT:
                x += 1
 
            # create line
            myscreen.set_at((x,y), (0,0,0))