!/usr/bin/env python

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)

#This assigns the pins of the raspberry pie to variables called "pin".
pin0 = 18
pin1 = 23
pin2 = 24
pin3 = 17

#
GPIO.setup(pin0, GPIO.OUT)
GPIO.setup(pin1, GPIO.OUT)
GPIO.setup(pin2, GPIO.OUT)
GPIO.setup(pin3, GPIO.OUT)

#Zero all of the pins between tests.
def zero_pins():
    time.sleep(0.1)
    GPIO.output(pin0, 0)
    GPIO.output(pin1, 0)
    GPIO.output(pin2, 0)
    GPIO.output(pin3, 0)

#This runs the test.
def test():
     
        zero_pins()
        print "Next - pin 0 test."
     
        GPIO.output(pin0, 1)
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin1, 1)
        zero_pins()                                          
        print "pin 0, pin 1"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        GPIO.output(pin0, 1)
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin2, 1)
        zero_pins()                                                  
        print "pin 0, pin 2"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        GPIO.output(pin0, 1)      
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin3, 1)      
        print "pin 0, pin 3"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        print "Next - pin 1 test."
     
        GPIO.output(pin1, 1)      
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin0, 1)        
        zero_pins()                                          
        print "pin 1, pin 0"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        GPIO.output(pin1, 1)      
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin2, 1)    
        zero_pins()                                                  
        print "pin 0, pin 2"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        GPIO.output(pin1, 1)      
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin3, 1)  
        zero_pins()                                          
        print "pin 0, pin 3"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        print "Next - pin 2 test."
     
        GPIO.output(pin2, 1)    
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin0, 1)    
        zero_pins()                                          
        print "pin 2, pin 0"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        GPIO.output(pin2, 1)      
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin1, 1)  
        zero_pins()                                          
        print "pin 2, pin 1"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        GPIO.output(pin2, 1)    
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin3, 1)    
        zero_pins()                                          
        print "pin 2, pin 3"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        print "Next - pin 3 test."
     
        GPIO.output(pin3, 1)      
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin0, 1)
        zero_pins()                                          
        print "pin 3, pin 0"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        GPIO.output(pin3, 1)    
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin1, 1)  
        zero_pins()                                          
        print "pin 3, pin 1"
        zero_pins()
        time.sleep(1)
        time.sleep(1)
     
        GPIO.output(pin3, 1)    
        zero_pins()          
        time.sleep(1)
        GPIO.output(pin2, 1)  
        zero_pins()                                          
        print "pin 3, pin 2"
        zero_pins()
        time.sleep(1)
        time.sleep(1)

test()