# Start by importing lib files "machine" & "time"
# Imports the machine module, which provides access to hardware features such as GPIO pins, ADCs, PWM, etc.
import machine
# Imports the time module, which provides delay functions like sleep().
import time

#we're initalizing pin 25 (which is the onboard LED) & GPIO pins 2, 6 and 10 as outputs (These are the GPIO numbers, not the actual pin numbers around the PCB).
# Creates a pin object called led1.
# Uses GPIO pin 25.
# Sets the pin mode to output (Pin.OUT).
# On a Raspberry Pi Pico, GPIO 25 is usually connected to the onboard LED.
led1 = machine.Pin(25, machine.Pin.OUT)
# Creates an output pin object for GPIO 2 (GP2).
led2 = machine.Pin(2, machine.Pin.OUT)
# Creates an output pin object for GPIO 6 (GP6).
led3 = machine.Pin(6, machine.Pin.OUT)
# Creates an output pin object for GPIO 10 (GP10).
led4 = machine.Pin(10, machine.Pin.OUT)

#Run a loop 5 times
# Starts a loop that repeats 5 times.
# The variable i takes values from 0 to 5.
for i in range(5):
# Sets GPIO 2 HIGH (3.3V).
# Turns LED 2 on (assuming the LED is wired active-high).
    led2.value(1)
# Sets GPIO 6 & 10 LOW.
# Turns LED 3 and 4 off.
    led3.value(0)
    led4.value(0)
    
    #Use time to wait for 0.5 second
    time.sleep(0.2)

# The rest of the code is a repetition of what has been done above. 
    #Turn the onbaord LED off
    led1.value(0)
    
    #Turn external LED on pin 2 (only) on
    #led1.value(0)
    led2.value(1)
    led3.value(0)
    led4.value(0)
    #Use time to wait for 1 second
    time.sleep(0.11)
    #Turn external LED on pin 3 (only) on
    #led1.value(0)
    led2.value(0)
    led3.value(1)
    led4.value(0)
    #Use time to wait for 1 second
    time.sleep(0.2)
    #Turn external LED on pin 4 (only) on
    #led1.value(0)
    led2.value(0)
    led3.value(0)
    led4.value(1)
    #Use time to wait for 1 second
    time.sleep(0.2)
    
    #Turn the external LED on pin 4 off
    led4.value(0)