Program Crashes unsure why - python-3.x

Question

Hello i'm trying to make a simple program to change the background colour on key press but it just crashes. It's to do with my loop but i don't really understand why it crashes.
thanks
import sys, pygame, random, time
from threading import Thread
pygame.init()
black = (0, 0, 0)
white = (255, 255, 255)
green = (0, 100, 0)
red = (255, 0, 0)
Colour = (0,0,0)
size = width, height = 350, 350
screen = pygame.display.set_mode(size)
Running = True
while True:
key = pygame.key.get_pressed()
if key[pygame.K_ESCAPE]: # Escape key
Running = False
elif key[pygame.K_DOWN]: # down key
print("down")
Colour = red
elif key[pygame.K_UP]: # up key
print("h")
Colour = black
elif key[pygame.K_RIGHT]: # right key
Colour = green
print("h")
elif key[pygame.K_LEFT]: # left key
Colour = white
print("h")
pygame.draw.rect(screen, Colour, pygame.Rect(0, 0, width, height))
pygame.display.update()
pygame.display.flip()

Answer 1

You're missing a way for pygame to know if you want to quit the window. Instead of doing key = pygame.key.get_pressed() use:
for event in pygame.event.get():
if event.type == QUIT:
pygame.quit()
sys.exit()
if event.type == KEYDOWN:
if event.key == K_ESCAPE:
pygame.quit()
sys.exit
if event.key == K_UP:
Colour = black
if event.key == K_DOWN:
Colour = red
if event.key == K_LEFT:
Colour = white
if event.key == K_RIGHT:
Colour = green
You also need a way for the program to handle time e.g. not run faster than you can see. You can do this by setting this variable at the top of your code:
clock = pygame.time.Clock()
and running this at the very end of your while loop:
clock.tick(FPS)
where you set the FPS as a number equal to the desired frames per second.
You can also remove your Running = True variable from the program. That should be all you need to get it running. Good luck! Ask questions below.

Answer 2

Two things:
You have a bug: the while loop while go forever because you are testing while True instead of while Running. You could change to while Running or after testing for escape key, you could break to exit the while loop.
Also, all pygame examples I have looked up just now have an event checker. Without that, pygame freezes. If you add it, everything is smooth.
Here are both of those corrected:
import sys, pygame, time
pygame.init()
size = 350, 350
screen = pygame.display.set_mode(size)
Running = True
while Running: # <----- changed this from True to Running
time.sleep(0.03) # avoid blasting the CPU. I think pygame.time.Clock also exists
# this makes pygame responsive
for event in pygame.event.get():
if event.type == pygame.QUIT:
Running = False # <---- or you could just break
# from here is as you originally wrote
key = pygame.key.get_pressed()
if key[pygame.K_ESCAPE]:
print('exit')
Running = False # <---- or you could just break
pygame.quit()
sys.exit()