import pygame

pygame.init()

BLACK = (  0,   0,   0)
WHITE = (255, 255, 255)
BLUE =  (  0,   0, 255)
GREEN = (  0, 255,   0)
RED =   (255,   0,   0)

size = [600, 600]
screen = pygame.display.set_mode(size)

done = False
clock = pygame.time.Clock()
screen.fill(WHITE)

while not done:

    # This limits the while loop to a max of 10 times per second.
    # Leave this out and we will use all CPU we can.
    clock.tick(10)

    for event in pygame.event.get(): # User did something
        if event.type == pygame.QUIT: # If user clicked close
            done = True # Flag that we are done so we exit this loop
    x = [10, 10]
    y = [10, 280]
    for i in range(10):
        if i % 3 == 0:
            depth = 4
        else:
            depth = 2
        pygame.draw.line(screen, BLACK, x, y, depth)
        x[0] = x[0] + 30
        y[0] = y[0] + 30
    x = [10, 10]
    y = [280, 10]
    for i in range(10):
        if i % 3 == 0:
            depth = 4
        else:
            depth = 2
        pygame.draw.line(screen, BLACK, x, y, depth)
        x[1] = x[1] + 30
        y[1] = y[1] + 30