Raspberry Pi 3 GPIO testing pushbutton input and LED output

gptest.py

#!/usr/bin/python

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BOARD)

BTN_G = 11 # G17
BTN_R = 12 # G18
BTN_Y = 13 # G27
BTN_B = 15 # G22

LED_G = 29 # G5
LED_R = 31 # G6
LED_Y = 32 # G12
LED_B = 33 # G13


GPIO.setup([BTN_G, BTN_R, BTN_Y, BTN_B], GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

GPIO.setup([LED_G, LED_R, LED_Y, LED_B], GPIO.OUT, initial=GPIO.LOW)

x = GPIO.HIGH
blink = False
blink_delay = 0.1
while True:
	[g, r, y, b] = [GPIO.input(BTN_G), GPIO.input(BTN_R), GPIO.input(BTN_Y), GPIO.input(BTN_B)]
	#print [g,r,y,b]

	# light corresponding LED when pushbutton of same color is pressed
	GPIO.output(LED_G, not g)
	GPIO.output(LED_R, not r)
	GPIO.output(LED_Y, not y)
	GPIO.output(LED_B, not b)

	# when green and red pressed, enter blink mode
	if g and r:
		blink = True
	elif g or r:
		blink = False
		blink_delay = 0.1

	if blink:
		if y: blink_delay += 0.1
		if b: blink_delay -= 0.1
		if blink_delay < 0: blink_delay = 0

		GPIO.output([LED_G, LED_R, LED_Y, LED_B], x)
		if x == GPIO.LOW:
			x = GPIO.HIGH
		else:
			x = GPIO.LOW

		time.sleep(blink_delay)
	time.sleep(0.01)

# TODO: interrupts vs polling?