Raspberry Pi Traffic Light

My son Alex and I worked on this over the weekend. It's a basic traffic light with a pedestrian button for the raspberry pi. To see a live video of it, check out my youtube channel.
​Here is the code and a schematic:

# Basic Traffic light with pedestrian button.
#
# Usage: sudo python3 pedtraffic.py
#
# This traffic light has adjustable timer durations for the red, yellow,
# and green lights, as well as a pedestrian button. When a pedestrian walks
# up and presses the button, the state of the button is saved and when the
# cycle comes back to green, it allows the pedestrian to walk with a green
# light on the tri-color LED. Once the traffic light goes yellow, the
# pedestrian light flashes blue, indicating they have just a little time to
# continue to cross. Once the traffic light is red, the ped light is also red.
#
# Written by Keith and Alex Cochran 8/10/19
# for Raspberry Pi Model B Rev 2 (26 pin)
#
# Hardware config:
# red led positive (+) lead to GPIO 17 (pin 11)
# yellow led positive (+) lead to GPIO 27 (pin 13)
# green led positive (+) lead to GPIO 22(pin 15)
# Used 220 ohm resistor to ground all LEDs (pin 25).
#
# Pedestrian button input goes to GPIO 15 (pin 10).
# Tri-color LED GPIOs used on 8, 7 and 4 for red, green and blue respectively. 
# Pin numbers for LEDs are 24 (red), 26 (green), 7 (blue)

import RPi.GPIO as GPIO
import time

pedestrian = False
pedCrossed = False

# Traffic light pins
red = 22
yellow = 27
green = 17

# Pedestrian light pins
b = 4
g = 7
r = 8
button = 15

# Traffic light durations, in seconds
redDuration = 10
yellowDuration = 5
greenDuration = 12

def button_callback(channel):
    print("Pedestrian pressed the cross walk button.") 
    global pedestrian
    pedestrian = True
    global pedCrossed
    pedCrossed = False

def on(n):
    GPIO.output(n, True)

def off(n):
    GPIO.output(n, False)

def allOff():
    off(red)
    off(yellow)
    off(green)
    off(b)
    off(g)
    off(r)

def allOnTest():
    on(red)
    on(yellow)
    on(green)
    pedRed()
    time.sleep(1)
    pedGreen()
    time.sleep(1)
    pedFlashBlue()
    time.sleep(1)
    allOff()

def init():
    GPIO.setmode(GPIO.BCM)
    GPIO.setwarnings(False)
    GPIO.setup(red, GPIO.OUT)
    GPIO.setup(yellow, GPIO.OUT)
    GPIO.setup(green, GPIO.OUT)
    GPIO.setup(b, GPIO.OUT)
    GPIO.setup(g, GPIO.OUT)
    GPIO.setup(r, GPIO.OUT)
    allOff()
    allOnTest()
    GPIO.setup(button, GPIO.IN, pull_up_down=GPIO.PUD_UP)
    GPIO.add_event_detect(button, GPIO.RISING, callback=button_callback)

def pedRed():
    off(g)
    off(b)
    on(r)

def pedGreen():
    off(r)
    off(b)
    on(g)

def pedFlashBlue():
    global pedestrian
    global pedCrossed
    off(r)
    off(g)
    length = yellowDuration
    pedestrian = False
    pedCrossed = False
    while length > 0:
        on(b)
        time.sleep(.5)
        length = length - 1
        off(b)
        time.sleep(.5)
    off(b)

def runLights():
    global pedestrian
    global pedCrossed
    off(red)
    on(green)
    if pedestrian:
        pedGreen()
        pedCrossed = True
    else:
        pedRed()
    time.sleep(greenDuration)
    off(green)
    on(yellow)
    if pedestrian and pedCrossed:
        pedFlashBlue()
    else:
        time.sleep(yellowDuration)
    off(yellow)
    on(red)
    pedRed()
    time.sleep(redDuration)

init()
while True:
    runLights()