diff --git a/Code/Python_Code/01.1.1_Blink/Blink.py b/Code/Python_Code/01.1.1_Blink/Blink.py
index d9caa7f..e0996b9 100644
--- a/Code/Python_Code/01.1.1_Blink/Blink.py
+++ b/Code/Python_Code/01.1.1_Blink/Blink.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : Blink.py
 # Description : Make an led blinking.
 # auther      : www.freenove.com
-# modification: 2018/08/02
+# modification: 2016/06/07
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -14,15 +14,15 @@ def setup():
 	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
 	GPIO.setup(ledPin, GPIO.OUT)   # Set ledPin's mode is output
 	GPIO.output(ledPin, GPIO.LOW) # Set ledPin low to off led
-	print ('using pin%d'%ledPin)
+	print 'using pin%d'%ledPin
 
 def loop():
 	while True:
 		GPIO.output(ledPin, GPIO.HIGH)  # led on
-		print ('...led on')
+		print '...led on'
 		time.sleep(1)	
 		GPIO.output(ledPin, GPIO.LOW) # led off
-		print ('led off...')
+		print 'led off...'
 		time.sleep(1)
 
 def destroy():
diff --git a/Code/Python_Code/02.1.1_ButtonLED/ButtonLED.py b/Code/Python_Code/02.1.1_ButtonLED/ButtonLED.py
index 65d9bad..bcb53ec 100644
--- a/Code/Python_Code/02.1.1_ButtonLED/ButtonLED.py
+++ b/Code/Python_Code/02.1.1_ButtonLED/ButtonLED.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : ButtonLED.py
 # Description : Controlling an led by button.
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/12
 ########################################################################
 import RPi.GPIO as GPIO
 
@@ -11,7 +11,7 @@ ledPin = 11    # define the ledPin
 buttonPin = 12    # define the buttonPin
 
 def setup():
-	print ('Program is starting...')
+	print 'Program is starting...'
 	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
 	GPIO.setup(ledPin, GPIO.OUT)   # Set ledPin's mode is output
 	GPIO.setup(buttonPin, GPIO.IN, pull_up_down=GPIO.PUD_UP)    # Set buttonPin's mode is input, and pull up to high level(3.3V)
@@ -20,10 +20,10 @@ def loop():
 	while True:
 		if GPIO.input(buttonPin)==GPIO.LOW:
 			GPIO.output(ledPin,GPIO.HIGH)
-			print ('led on ...')
+			print 'led on ...'
 		else :
 			GPIO.output(ledPin,GPIO.LOW)
-			print ('led off ...')		
+			print 'led off ...'		
 
 def destroy():
 	GPIO.output(ledPin, GPIO.LOW)     # led off
diff --git a/Code/Python_Code/02.2.1_Tablelamp/Tablelamp.py b/Code/Python_Code/02.2.1_Tablelamp/Tablelamp.py
index 12d2bf0..a5b70e0 100644
--- a/Code/Python_Code/02.2.1_Tablelamp/Tablelamp.py
+++ b/Code/Python_Code/02.2.1_Tablelamp/Tablelamp.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : Tablelamp.py
 # Description : a DIY MINI table lamp
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/12
 ########################################################################
 import RPi.GPIO as GPIO
 
@@ -12,19 +12,19 @@ buttonPin = 12    # define the buttonPin
 ledState = False
 
 def setup():
-	print ('Program is starting...')
+	print 'Program is starting...'
 	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
 	GPIO.setup(ledPin, GPIO.OUT)   # Set ledPin's mode is output
 	GPIO.setup(buttonPin, GPIO.IN, pull_up_down=GPIO.PUD_UP)    # Set buttonPin's mode is input, and pull up to high
 
 def buttonEvent(channel):#When the button is pressed, this function will be executed
 	global ledState 
-	print ('buttonEvent GPIO%d' %channel)
+	print 'buttonEvent GPIO%d'%channel
 	ledState = not ledState
 	if ledState :
-		print ('Turn on LED ... ')
+		print 'Turn on LED ... '
 	else :
-		print ('Turn off LED ... ')
+		print 'Turn off LED ... '
 	GPIO.output(ledPin,ledState)
 	
 def loop():
diff --git a/Code/Python_Code/03.1.1_LightWater/LightWater.py b/Code/Python_Code/03.1.1_LightWater/LightWater.py
index 1212533..f0f3fc8 100644
--- a/Code/Python_Code/03.1.1_LightWater/LightWater.py
+++ b/Code/Python_Code/03.1.1_LightWater/LightWater.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : LightWater.py
 # Description : Display 10 LEDBar Graph
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/13
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -11,7 +11,7 @@ import time
 ledPins = [11, 12, 13, 15, 16, 18, 22, 3, 5, 24]
 
 def setup():
-	print ('Program is starting...')
+	print 'Program is starting...'
 	GPIO.setmode(GPIO.BOARD)        # Numbers GPIOs by physical location
 	for pin in ledPins:
 		GPIO.setup(pin, GPIO.OUT)   # Set all ledPins' mode is output
diff --git a/Code/Python_Code/04.1.1_BreathingLED/BreathingLED.py b/Code/Python_Code/04.1.1_BreathingLED/BreathingLED.py
index ad24fea..1597e2c 100644
--- a/Code/Python_Code/04.1.1_BreathingLED/BreathingLED.py
+++ b/Code/Python_Code/04.1.1_BreathingLED/BreathingLED.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : BreathingLED.py
 # Description : A breathing LED
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/14
 ########################################################################
 import RPi.GPIO as GPIO
 import time
diff --git a/Code/Python_Code/05.1.1_ColorfulLED/ColorfulLED.py b/Code/Python_Code/05.1.1_ColorfulLED/ColorfulLED.py
index 6733286..ccdcd5c 100644
--- a/Code/Python_Code/05.1.1_ColorfulLED/ColorfulLED.py
+++ b/Code/Python_Code/05.1.1_ColorfulLED/ColorfulLED.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : ColorfulLED.py
 # Description : A auto flash ColorfulLED
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/15
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -13,7 +13,7 @@ pins = {'pin_R':11, 'pin_G':12, 'pin_B':13}  # pins is a dict
 
 def setup():
 	global p_R,p_G,p_B
-	print ('Program is starting ... ')
+	print 'Program is starting ... '
 	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
 	for i in pins:
 		GPIO.setup(pins[i], GPIO.OUT)   # Set pins' mode is output
@@ -36,7 +36,7 @@ def loop():
 		g=random.randint(0,100)
 		b=random.randint(0,100)
 		setColor(r,g,b)#set random as a duty cycle value 
-		print ('r=%d, g=%d, b=%d ' %(r ,g, b))
+		print 'r=%d, g=%d, b=%d '%(r ,g, b)
 		time.sleep(0.3)
 		
 def destroy():
diff --git a/Code/Python_Code/06.1.1_Doorbell/Doorbell.py b/Code/Python_Code/06.1.1_Doorbell/Doorbell.py
index e951384..c038f9e 100644
--- a/Code/Python_Code/06.1.1_Doorbell/Doorbell.py
+++ b/Code/Python_Code/06.1.1_Doorbell/Doorbell.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : Doorbell.py
 # Description : Controlling an buzzer by button.
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/12
 ########################################################################
 import RPi.GPIO as GPIO
 
@@ -11,7 +11,7 @@ buzzerPin = 11    # define the buzzerPin
 buttonPin = 12    # define the buttonPin
 
 def setup():
-	print ('Program is starting...')
+	print 'Program is starting...'
 	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
 	GPIO.setup(buzzerPin, GPIO.OUT)   # Set buzzerPin's mode is output
 	GPIO.setup(buttonPin, GPIO.IN, pull_up_down=GPIO.PUD_UP)    # Set buttonPin's mode is input, and pull up to high level(3.3V)
@@ -20,10 +20,10 @@ def loop():
 	while True:
 		if GPIO.input(buttonPin)==GPIO.LOW:
 			GPIO.output(buzzerPin,GPIO.HIGH)
-			print ('buzzer on ...')
+			print 'buzzer on ...'
 		else :
 			GPIO.output(buzzerPin,GPIO.LOW)
-			print ('buzzer off ...')
+			print 'buzzer off ...'		
 
 def destroy():
 	GPIO.output(buzzerPin, GPIO.LOW)     # buzzer off
diff --git a/Code/Python_Code/06.2.1_Alertor/Alertor.py b/Code/Python_Code/06.2.1_Alertor/Alertor.py
index 73ea16f..bbfb6e6 100644
--- a/Code/Python_Code/06.2.1_Alertor/Alertor.py
+++ b/Code/Python_Code/06.2.1_Alertor/Alertor.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : Alertor.py
 # Description : Alarm by button.
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/14
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -14,7 +14,7 @@ buttonPin = 12    # define the buttonPin
 
 def setup():
 	global p
-	print ('Program is starting...')
+	print 'Program is starting...'
 	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
 	GPIO.setup(buzzerPin, GPIO.OUT)   # Set buzzerPin's mode is output
 	GPIO.setup(buttonPin, GPIO.IN, pull_up_down=GPIO.PUD_UP)    # Set buttonPin's mode is input, and pull up to high level(3.3V)
@@ -25,10 +25,10 @@ def loop():
 	while True:
 		if GPIO.input(buttonPin)==GPIO.LOW:
 			alertor()
-			print ('buzzer on ...')
+			print 'buzzer on ...'
 		else :
 			stopAlertor()
-			print ('buzzer off ...')
+			print 'buzzer off ...'		
 def alertor():
 	p.start(50)
 	for x in range(0,361):		#frequency of the alarm along the sine wave change
diff --git a/Code/Python_Code/07.1.1_PCF8591/PCF8591.py b/Code/Python_Code/07.1.1_PCF8591/PCF8591.py
index e4381fb..80e0be1 100644
--- a/Code/Python_Code/07.1.1_PCF8591/PCF8591.py
+++ b/Code/Python_Code/07.1.1_PCF8591/PCF8591.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : PCF8591.py
 # Description : ADC and DAC
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/18
 ########################################################################
 import smbus
 import time
@@ -24,14 +24,14 @@ def loop():
 		value = analogRead(0)	#read the ADC value of channel 0
 		analogWrite(value)		#write the DAC value
 		voltage = value / 255.0 * 3.3  #calculate the voltage value
-		print ('ADC Value : %d, Voltage : %.2f'%(value,voltage))
+		print 'ADC Value : %d, Voltage : %.2f'%(value,voltage)
 		time.sleep(0.01)
 
 def destroy():
 	bus.close()
 	
 if __name__ == '__main__':
-	print ('Program is starting ... ')
+	print 'Program is starting ... '
 	try:
 		loop()
 	except KeyboardInterrupt:
diff --git a/Code/Python_Code/08.1.1_SoftLight/SoftLight.py b/Code/Python_Code/08.1.1_SoftLight/SoftLight.py
index 7a3cd88..fed1222 100644
--- a/Code/Python_Code/08.1.1_SoftLight/SoftLight.py
+++ b/Code/Python_Code/08.1.1_SoftLight/SoftLight.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : Softlight.py
 # Description : Potentiometer control LED
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/18
 ########################################################################
 import RPi.GPIO as GPIO
 import smbus
@@ -35,7 +35,7 @@ def loop():
 		value = analogRead(0)		#read A0 pin 
 		p.ChangeDutyCycle(value*100/255)		#Convert ADC value to duty cycle of PWM 
 		voltage = value / 255.0 * 3.3			#calculate voltage
-		print ('ADC Value : %d, Voltage : %.2f'%(value,voltage))
+		print 'ADC Value : %d, Voltage : %.2f'%(value,voltage)
 		time.sleep(0.01)
 
 def destroy():
@@ -43,7 +43,7 @@ def destroy():
 	GPIO.cleanup()
 	
 if __name__ == '__main__':
-	print ('Program is starting ... ')
+	print 'Program is starting ... '
 	setup()
 	try:
 		loop()
diff --git a/Code/Python_Code/09.1.1_ColorfulSoftlight/ColorfulSoftlight.py b/Code/Python_Code/09.1.1_ColorfulSoftlight/ColorfulSoftlight.py
index 57e951d..4278aae 100644
--- a/Code/Python_Code/09.1.1_ColorfulSoftlight/ColorfulSoftlight.py
+++ b/Code/Python_Code/09.1.1_ColorfulSoftlight/ColorfulSoftlight.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : Softlight.py
 # Description : Potentiometer control LED
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/18
 ########################################################################
 import RPi.GPIO as GPIO
 import smbus
@@ -49,7 +49,7 @@ def loop():
         p_Green.ChangeDutyCycle(value_Green*100/255)
         p_Blue.ChangeDutyCycle(value_Blue*100/255)
         #print read ADC value
-        print ('ADC Value value_Red: %d ,\tvlue_Green: %d ,\tvalue_Blue: %d'%(value_Red,value_Green,value_Blue))
+        print 'ADC Value value_Red: %d ,\tvlue_Green: %d ,\tvalue_Blue: %d'%(value_Red,value_Green,value_Blue)
         time.sleep(0.01)
 
 def destroy():
@@ -57,7 +57,7 @@ def destroy():
     GPIO.cleanup()
     
 if __name__ == '__main__':
-    print ('Program is starting ... ')
+    print 'Program is starting ... '
     setup()
     try:
         loop()
diff --git a/Code/Python_Code/10.1.1_Nightlamp/Nightlamp.py b/Code/Python_Code/10.1.1_Nightlamp/Nightlamp.py
index 5579e66..86b28c5 100644
--- a/Code/Python_Code/10.1.1_Nightlamp/Nightlamp.py
+++ b/Code/Python_Code/10.1.1_Nightlamp/Nightlamp.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : Nightlamp.py
 # Description : Photoresistor control LED
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/18
 ########################################################################
 import RPi.GPIO as GPIO
 import smbus
@@ -35,7 +35,7 @@ def loop():
 		value = analogRead(0)
 		p.ChangeDutyCycle(value*100/255)
 		voltage = value / 255.0 * 3.3
-		print ('ADC Value : %d, Voltage : %.2f'%(value,voltage))
+		print 'ADC Value : %d, Voltage : %.2f'%(value,voltage)
 		time.sleep(0.01)
 
 def destroy():
@@ -43,7 +43,7 @@ def destroy():
 	GPIO.cleanup()
 	
 if __name__ == '__main__':
-	print ('Program is starting ... ')
+	print 'Program is starting ... '
 	setup()
 	try:
 		loop()
diff --git a/Code/Python_Code/11.1.1_Thermometer/Thermometer.py b/Code/Python_Code/11.1.1_Thermometer/Thermometer.py
index c489ed9..dd0259e 100644
--- a/Code/Python_Code/11.1.1_Thermometer/Thermometer.py
+++ b/Code/Python_Code/11.1.1_Thermometer/Thermometer.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : Thermometer.py
 # Description : A DIY Thermometer
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/20
 ########################################################################
 import RPi.GPIO as GPIO
 import smbus
@@ -31,14 +31,14 @@ def loop():
 		Rt = 10 * voltage / (3.3 - voltage)	#calculate resistance value of thermistor
 		tempK = 1/(1/(273.15 + 25) + math.log(Rt/10)/3950.0) #calculate temperature (Kelvin)
 		tempC = tempK -273.15		#calculate temperature (Celsius)
-		print ('ADC Value : %d, Voltage : %.2f, Temperature : %.2f'%(value,voltage,tempC))
+		print 'ADC Value : %d, Voltage : %.2f, Temperature : %.2f'%(value,voltage,tempC)
 		time.sleep(0.01)
 
 def destroy():
 	GPIO.cleanup()
 	
 if __name__ == '__main__':
-	print ('Program is starting ... ')
+	print 'Program is starting ... '
 	setup()
 	try:
 		loop()
diff --git a/Code/Python_Code/12.1.1_Joystick/Joystick.py b/Code/Python_Code/12.1.1_Joystick/Joystick.py
index c367e32..7509463 100644
--- a/Code/Python_Code/12.1.1_Joystick/Joystick.py
+++ b/Code/Python_Code/12.1.1_Joystick/Joystick.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : Joystick.py
 # Description : Read Joystick
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/18
 ########################################################################
 import RPi.GPIO as GPIO
 import smbus
@@ -32,7 +32,7 @@ def loop():
         val_Z = GPIO.input(Z_Pin)       #read digital quality of axis Z
         val_Y = analogRead(0)           #read analog quality of axis X and Y
         val_X = analogRead(1)
-        print ('value_X: %d ,\tvlue_Y: %d ,\tvalue_Z: %d'%(val_X,val_Y,val_Z))
+        print 'value_X: %d ,\tvlue_Y: %d ,\tvalue_Z: %d'%(val_X,val_Y,val_Z)
         time.sleep(0.01)
 
 def destroy():
@@ -40,7 +40,7 @@ def destroy():
     GPIO.cleanup()
     
 if __name__ == '__main__':
-    print ('Program is starting ... ')
+    print 'Program is starting ... '
     setup()
     try:
         loop()
diff --git a/Code/Python_Code/13.1.1_Motor/Motor.py b/Code/Python_Code/13.1.1_Motor/Motor.py
index feb17f0..42c9e40 100644
--- a/Code/Python_Code/13.1.1_Motor/Motor.py
+++ b/Code/Python_Code/13.1.1_Motor/Motor.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : Motor.py
 # Description : Control Motor by L293D
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/21
 ########################################################################
 import RPi.GPIO as GPIO
 import smbus
@@ -43,22 +43,22 @@ def motor(ADC):
     if (value > 0):
         GPIO.output(motoRPin1,GPIO.HIGH)
         GPIO.output(motoRPin2,GPIO.LOW)
-        print ('Turn Forward...')
+        print 'Turn Forward...'
     elif (value < 0):
         GPIO.output(motoRPin1,GPIO.LOW)
         GPIO.output(motoRPin2,GPIO.HIGH)
-        print ('Turn Backward...')
+        print 'Turn Backward...'
     else :
         GPIO.output(motoRPin1,GPIO.LOW)
         GPIO.output(motoRPin2,GPIO.LOW)
-        print ('Motor Stop...')
+        print 'Motor Stop...'
     p.start(mapNUM(abs(value),0,128,0,100))
-    print ('The PWM duty cycle is %d%%\n'%(abs(value)*100/127))   #print PMW duty cycle.
+    print 'The PWM duty cycle is %d%%\n'%(abs(value)*100/127)   #print PMW duty cycle.
 
 def loop():
     while True:
         value = analogRead(0)
-        print ('ADC Value : %d'%(value))
+        print 'ADC Value : %d'%(value)
         motor(value)
         time.sleep(0.01)
 
@@ -67,7 +67,7 @@ def destroy():
     GPIO.cleanup()
     
 if __name__ == '__main__':
-    print ('Program is starting ... ')
+    print 'Program is starting ... '
     setup()
     try:
         loop()
diff --git a/Code/Python_Code/14.1.1_Relay/Relay.py b/Code/Python_Code/14.1.1_Relay/Relay.py
index 615497b..6dec590 100644
--- a/Code/Python_Code/14.1.1_Relay/Relay.py
+++ b/Code/Python_Code/14.1.1_Relay/Relay.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : Relay.py
 # Description : Button control Relay and Motor
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/07/04
 ########################################################################
 import RPi.GPIO as GPIO
 
@@ -12,19 +12,19 @@ buttonPin = 12    # define the buttonPin
 relayState = False
 
 def setup():
-	print ('Program is starting...')
+	print 'Program is starting...'
 	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
 	GPIO.setup(relayPin, GPIO.OUT)   # Set relayPin's mode is output
 	GPIO.setup(buttonPin, GPIO.IN, pull_up_down=GPIO.PUD_UP)    # Set buttonPin's mode is input, and pull up to high
 
 def buttonEvent(channel):
 	global relayState 
-	print ('buttonEvent GPIO%d'%channel)
+	print 'buttonEvent GPIO%d'%channel
 	relayState = not relayState
 	if relayState :
-		print ('Turn on relay ... ')
+		print 'Turn on relay ... '
 	else :
-		print ('Turn off relay ... ')
+		print 'Turn off relay ... '
 	GPIO.output(relayPin,relayState)
 	
 def loop():
diff --git a/Code/Python_Code/15.1.1_Sweep/Sweep.py b/Code/Python_Code/15.1.1_Sweep/Sweep.py
index d561224..89f941a 100644
--- a/Code/Python_Code/15.1.1_Sweep/Sweep.py
+++ b/Code/Python_Code/15.1.1_Sweep/Sweep.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : Sweep.py
 # Description : Servo sweep
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/07/06
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -47,7 +47,7 @@ def destroy():
     GPIO.cleanup()
 
 if __name__ == '__main__':     #Program start from here
-    print ('Program is starting...')
+    print 'Program is starting...'
     setup()
     try:
         loop()
diff --git a/Code/Python_Code/16.1.1_SteppingMotor/SteppingMotor.py b/Code/Python_Code/16.1.1_SteppingMotor/SteppingMotor.py
index 9b06933..67992df 100644
--- a/Code/Python_Code/16.1.1_SteppingMotor/SteppingMotor.py
+++ b/Code/Python_Code/16.1.1_SteppingMotor/SteppingMotor.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : SteppingMotor.py
 # Description : 
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/07/07
 ########################################################################
 import RPi.GPIO as GPIO
 import time 
@@ -13,7 +13,7 @@ CCWStep = (0x01,0x02,0x04,0x08) #define power supply order for coil for rotating
 CWStep = (0x08,0x04,0x02,0x01)  #define power supply order for coil for rotating clockwise
 
 def setup():
-    print ('Program is starting...')
+    print 'Program is starting...'
     GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
     for pin in motorPins:
         GPIO.setup(pin,GPIO.OUT)
diff --git a/Code/Python_Code/17.1.1_LightWater02/LightWater02.py b/Code/Python_Code/17.1.1_LightWater02/LightWater02.py
index f0d7861..97b7dce 100644
--- a/Code/Python_Code/17.1.1_LightWater02/LightWater02.py
+++ b/Code/Python_Code/17.1.1_LightWater02/LightWater02.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : LightWater02.py
 # Description : Control LED by 74HC595
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/23
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -51,7 +51,7 @@ def destroy():   # When 'Ctrl+C' is pressed, the function is executed.
 	GPIO.cleanup()
 
 if __name__ == '__main__': # Program starting from here 
-	print ('Program is starting...' )
+	print 'Program is starting...' 
 	setup() 
 	try:
 		loop()  
diff --git a/Code/Python_Code/18.1.1_SevenSegmentDisplay/SevenSegmentDisplay.py b/Code/Python_Code/18.1.1_SevenSegmentDisplay/SevenSegmentDisplay.py
index a08da9a..d7200a2 100644
--- a/Code/Python_Code/18.1.1_SevenSegmentDisplay/SevenSegmentDisplay.py
+++ b/Code/Python_Code/18.1.1_SevenSegmentDisplay/SevenSegmentDisplay.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : SevenSegmentDisplay.py
 # Description : Control SevenSegmentDisplay by 74HC595
 # Author      : freenove
-# modification: 2018/08/02
+# modification: 2016/06/24
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -48,7 +48,7 @@ def destroy():   # When 'Ctrl+C' is pressed, the function is executed.
 	GPIO.cleanup()
 
 if __name__ == '__main__': # Program starting from here 
-	print ('Program is starting...' )
+	print 'Program is starting...' 
 	setup() 
 	try:
 		loop()  
diff --git a/Code/Python_Code/18.2.1_StopWatch/StopWatch.py b/Code/Python_Code/18.2.1_StopWatch/StopWatch.py
index c2bcd75..8409b4f 100644
--- a/Code/Python_Code/18.2.1_StopWatch/StopWatch.py
+++ b/Code/Python_Code/18.2.1_StopWatch/StopWatch.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : StopWatch.py
 # Description : Control 4_Digit_7_Segment_Display by 74HC595
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2016/07/08
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -16,9 +16,9 @@ dataPin   = 18      #DS Pin of 74HC595(Pin14)
 latchPin  = 16      #ST_CP Pin of 74HC595(Pin12)
 clockPin = 12       #SH_CP Pin of 74HC595(Pin11)
 num = (0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90)
-digitPin = (11,13,15,19)    # Define the pin of 7-segment display common end
+digitPin = (19,15,13,11)    # Define the pin of 7-segment display common end
 counter = 0         # Variable counter, the number will be dislayed by 7-segment display
-t = 0               # define the Timer object
+t = 0               # defien the Timer object
 def setup():
     GPIO.setmode(GPIO.BOARD)    # Number GPIOs by its physical location
     GPIO.setup(dataPin, GPIO.OUT)       # Set pin mode to output
@@ -54,15 +54,15 @@ def display(dec):   #display function for 7-segment display
     time.sleep(0.003)   #display duration
     outData(0xff)
     selectDigit(0x02)   # Select the second, and display the tens digit
-    outData(num[dec%100//10])
+    outData(num[dec%100/10])
     time.sleep(0.003)
     outData(0xff)
     selectDigit(0x04)   # Select the third, and display the hundreds digit
-    outData(num[dec%1000//100])
+    outData(num[dec%1000/100])
     time.sleep(0.003)
     outData(0xff)
     selectDigit(0x08)   # Select the fourth, and display the thousands digit
-    outData(num[dec%10000//1000])
+    outData(num[dec%10000/1000])
     time.sleep(0.003)
 def timer():        #timer function
     global counter
@@ -70,7 +70,7 @@ def timer():        #timer function
     t = threading.Timer(1.0,timer)      #reset time of timer to 1s
     t.start()                           #Start timing
     counter+=1                          
-    print ("counter : %d"%counter)
+    print "counter : %d"%counter
     
 def loop():
     global t
@@ -86,7 +86,7 @@ def destroy():   # When "Ctrl+C" is pressed, the function is executed.
     t.cancel()      #cancel the timer
 
 if __name__ == '__main__': # Program starting from here 
-    print ('Program is starting...' )
+    print 'Program is starting...' 
     setup() 
     try:
         loop()  
diff --git a/Code/Python_Code/19.1.1_LEDMatrix/LEDMatrix.py b/Code/Python_Code/19.1.1_LEDMatrix/LEDMatrix.py
index 2b8a042..9ee08f3 100644
--- a/Code/Python_Code/19.1.1_LEDMatrix/LEDMatrix.py
+++ b/Code/Python_Code/19.1.1_LEDMatrix/LEDMatrix.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : LEDMatrix.py
 # Description : Control LEDMatrix by 74HC595
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2016/06/24
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -56,9 +56,9 @@ def loop():
             x=0x80
             for i in range(0,8):
                 GPIO.output(latchPin,GPIO.LOW)
-                shiftOut(dataPin,clockPin,MSBFIRST,pic[i]) #first shift data of line information to first stage 74HC959
+                shiftOut(dataPin,clockPin,LSBFIRST,pic[i]) #first shift data of line information to first stage 74HC959
 
-                shiftOut(dataPin,clockPin,MSBFIRST,~x) #then shift data of column information to second stage 74HC959
+                shiftOut(dataPin,clockPin,LSBFIRST,~x) #then shift data of column information to second stage 74HC959
                 GPIO.output(latchPin,GPIO.HIGH)# Output data of two stage 74HC595 at the same time
                 time.sleep(0.001)# display the next column
                 x>>=1
@@ -67,15 +67,15 @@ def loop():
                 x=0x80      # Set the column information to start from the first column
                 for i in range(k,k+8):
                     GPIO.output(latchPin,GPIO.LOW)
-                    shiftOut(dataPin,clockPin,MSBFIRST,data[i])
-                    shiftOut(dataPin,clockPin,MSBFIRST,~x)
+                    shiftOut(dataPin,clockPin,LSBFIRST,data[i])
+                    shiftOut(dataPin,clockPin,LSBFIRST,~x)
                     GPIO.output(latchPin,GPIO.HIGH)
                     time.sleep(0.001)
                     x>>=1
 def destroy():   # When 'Ctrl+C' is pressed, the function is executed. 
     GPIO.cleanup()
 if __name__ == '__main__': # Program starting from here 
-    print ('Program is starting...' )
+    print 'Program is starting...' 
     setup() 
     try:
         loop()  
diff --git a/Code/Python_Code/20.1.1_I2CLCD1602/Adafruit_LCD1602.pyc b/Code/Python_Code/20.1.1_I2CLCD1602/Adafruit_LCD1602.pyc
new file mode 100644
index 0000000..2e53d78
Binary files /dev/null and b/Code/Python_Code/20.1.1_I2CLCD1602/Adafruit_LCD1602.pyc differ
diff --git a/Code/Python_Code/20.1.1_I2CLCD1602/I2CLCD1602.py b/Code/Python_Code/20.1.1_I2CLCD1602/I2CLCD1602.py
index 4e4472b..eb48bda 100644
--- a/Code/Python_Code/20.1.1_I2CLCD1602/I2CLCD1602.py
+++ b/Code/Python_Code/20.1.1_I2CLCD1602/I2CLCD1602.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : I2CLCD1602.py
 # Description : Use the LCD display data
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2017/04/18
 ########################################################################
 from PCF8574 import PCF8574_GPIO
 from Adafruit_LCD1602 import Adafruit_CharLCD
@@ -42,13 +42,13 @@ except:
 	try:
 		mcp = PCF8574_GPIO(PCF8574A_address)
 	except:
-		print ('I2C Address Error !')
+		print 'I2C Address Error !'
 		exit(1)
 # Create LCD, passing in MCP GPIO adapter.
 lcd = Adafruit_CharLCD(pin_rs=0, pin_e=2, pins_db=[4,5,6,7], GPIO=mcp)
 
 if __name__ == '__main__':
-    print ('Program is starting ... ')
+    print 'Program is starting ... '
     try:
         loop()
     except KeyboardInterrupt:
diff --git a/Code/Python_Code/20.1.1_I2CLCD1602/PCF8574.py b/Code/Python_Code/20.1.1_I2CLCD1602/PCF8574.py
index 262d9b6..50fb5ce 100644
--- a/Code/Python_Code/20.1.1_I2CLCD1602/PCF8574.py
+++ b/Code/Python_Code/20.1.1_I2CLCD1602/PCF8574.py
@@ -2,7 +2,7 @@
 # Filename    : PCF8574.py
 # Description : PCF8574 as Raspberry GPIO
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2017/04/18
 ########################################################################
 import smbus
 import time
@@ -42,11 +42,11 @@ def loop():
 	while True:
 		#mcp.writeByte(0xff)
 		mcp.digitalWrite(3,1)
-		print ('Is 0xff? %x'%(mcp.readByte()))
+		print 'Is 0xff? %x'%(mcp.readByte())
 		time.sleep(1)
 		mcp.writeByte(0x00)
 		#mcp.digitalWrite(7,1)
-		print ('Is 0x00? %x'%(mcp.readByte()))
+		print 'Is 0x00? %x'%(mcp.readByte())
 		time.sleep(1)
 		
 class PCF8574_GPIO(object):#Standardization function interface
@@ -70,7 +70,7 @@ def destroy():
 	bus.close()
 	
 if __name__ == '__main__':
-	print ('Program is starting ... ')
+	print 'Program is starting ... '
 	try:
 		loop()
 	except KeyboardInterrupt:
diff --git a/Code/Python_Code/20.1.1_I2CLCD1602/PCF8574.pyc b/Code/Python_Code/20.1.1_I2CLCD1602/PCF8574.pyc
new file mode 100644
index 0000000..f06d07c
Binary files /dev/null and b/Code/Python_Code/20.1.1_I2CLCD1602/PCF8574.pyc differ
diff --git a/Code/Python_Code/21.1.1_DHT11/DHT11.py b/Code/Python_Code/21.1.1_DHT11/DHT11.py
index d8a16a9..31640eb 100644
--- a/Code/Python_Code/21.1.1_DHT11/DHT11.py
+++ b/Code/Python_Code/21.1.1_DHT11/DHT11.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : DHT11.py
 # Description :	read the temperature and humidity data of DHT11
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2018/03/07
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -16,21 +16,21 @@ def loop():
     while(True):
         sumCnt += 1         #counting number of reading times
         chk = dht.readDHT11()     #read DHT11 and get a return value. Then determine whether data read is normal according to the return value.
-        print ("The sumCnt is : %d, \t chk    : %d"%(sumCnt,chk))
+        print"The sumCnt is : %d, \t chk    : %d"%(sumCnt,chk)  
         if (chk is dht.DHTLIB_OK):      #read DHT11 and get a return value. Then determine whether data read is normal according to the return value.
-            print("DHT11,OK!")
+            print"DHT11,OK!"        
         elif(chk is dht.DHTLIB_ERROR_CHECKSUM): #data check has errors
-            print("DHTLIB_ERROR_CHECKSUM!!")
+            print"DHTLIB_ERROR_CHECKSUM!!"
         elif(chk is dht.DHTLIB_ERROR_TIMEOUT):  #reading DHT times out
-            print("DHTLIB_ERROR_TIMEOUT!")
+            print"DHTLIB_ERROR_TIMEOUT!"
         else:               #other errors
-            print("Other error!")
+            print"Other error!"
             
-        print("Humidity : %.2f, \t Temperature : %.2f \n"%(dht.humidity,dht.temperature))
+        print"Humidity : %.2f, \t Temperature : %.2f \n"%(dht.humidity,dht.temperature)     
         time.sleep(2)       
         
 if __name__ == '__main__':
-    print ('Program is starting ... ')
+    print 'Program is starting ... '
     try:
         loop()
     except KeyboardInterrupt:
diff --git a/Code/Python_Code/21.1.1_DHT11/Freenove_DHT.py b/Code/Python_Code/21.1.1_DHT11/Freenove_DHT.py
index 8fd9571..472bb93 100644
--- a/Code/Python_Code/21.1.1_DHT11/Freenove_DHT.py
+++ b/Code/Python_Code/21.1.1_DHT11/Freenove_DHT.py
@@ -1,9 +1,8 @@
-#!/usr/bin/env python3
 #############################################################################
 # Filename    : Freenove_DHT.py
 # Description :	DHT Temperature & Humidity Sensor library for Raspberry
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2018/03/07
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -40,32 +39,32 @@ class DHT(object):
 		t = time.time()
 		while(GPIO.input(pin) == GPIO.LOW):
 			if((time.time() - t) > loopCnt):
-				#print ("Echo LOW")
+				#print "Echo LOW"
 				return self.DHTLIB_ERROR_TIMEOUT
 		t = time.time()
 		while(GPIO.input(pin) == GPIO.HIGH):
 			if((time.time() - t) > loopCnt):
-				#print ("Echo HIGH")
+				#print "Echo HIGH"
 				return self.DHTLIB_ERROR_TIMEOUT
 		for i in range(0,40,1):
 			t = time.time()
 			while(GPIO.input(pin) == GPIO.LOW):
 				if((time.time() - t) > loopCnt):
-					#print ("Data Low %d"%(i))
+					#print "Data Low %d"%(i)
 					return self.DHTLIB_ERROR_TIMEOUT
 			t = time.time()
 			while(GPIO.input(pin) == GPIO.HIGH):
 				if((time.time() - t) > loopCnt):
-					#print ("Data HIGH %d"%(i))
+					#print "Data HIGH %d"%(i)
 					return self.DHTLIB_ERROR_TIMEOUT		
 			if((time.time() - t) > 0.00005):	
 				self.bits[idx] |= mask
-			#print("t : %f"%(time.time()-t))
+			#print"t : %f"%(time.time()-t)
 			mask >>= 1
 			if(mask == 0):
 				mask = 0x80
 				idx += 1	
-		#print (self.bits)
+		#print self.bits
 		GPIO.setup(pin,GPIO.OUT)
 		GPIO.output(pin,GPIO.HIGH)
 		return self.DHTLIB_OK
@@ -93,12 +92,12 @@ def loop():
 		if (chk is 0):
 			okCnt += 1		
 		okRate = 100.0*okCnt/sumCnt;
-		print("sumCnt : %d, \t okRate : %.2f%% "%(sumCnt,okRate))
-		print("chk : %d, \t Humidity : %.2f, \t Temperature : %.2f "%(chk,dht.humidity,dht.temperature))
+		print"sumCnt : %d, \t okRate : %.2f%% "%(sumCnt,okRate)		
+		print"chk : %d, \t Humidity : %.2f, \t Temperature : %.2f "%(chk,dht.humidity,dht.temperature)		
 		time.sleep(3)		
 		
 if __name__ == '__main__':
-	print ('Program is starting ... ')
+	print 'Program is starting ... '
 	try:
 		loop()
 	except KeyboardInterrupt:
diff --git a/Code/Python_Code/22.1.1_MatrixKeypad/Keypad.py b/Code/Python_Code/22.1.1_MatrixKeypad/Keypad.py
index 5c0729b..202be7a 100644
--- a/Code/Python_Code/22.1.1_MatrixKeypad/Keypad.py
+++ b/Code/Python_Code/22.1.1_MatrixKeypad/Keypad.py
@@ -1,4 +1,3 @@
-#!/usr/bin/env python3
 ########################################################################
 # Filename    : Keypad.py
 # Description : The module of matrix keypad 
@@ -187,15 +186,15 @@ rowsPins = [12,16,18,22]
 colsPins = [19,15,13,11]	
 
 def loop():
-	keypad = Keypad(keys,rowsPins,colsPins,ROWS,COLS)
+	keypad = Keypad.Keypad(keys,rowsPins,colsPins,ROWS,COLS)
 	keypad.setDebounceTime(50)
 	while(True):
 		key = keypad.getKey()
 		if(key != keypad.NULL):
-			print ("You Pressed Key : %c "%(key) )
+			print "You Pressed Key : %c "%(key) 
 			
 if __name__ == '__main__':     # Program start from here
-	print ("Program is starting ... ")
+	print "Program is starting ... "
 	try:
 		loop()
 	except KeyboardInterrupt:  # When 'Ctrl+C' is pressed, the child program destroy() will be  executed.
diff --git a/Code/Python_Code/22.1.1_MatrixKeypad/MatrixKeypad.py b/Code/Python_Code/22.1.1_MatrixKeypad/MatrixKeypad.py
index db852f8..1141fab 100644
--- a/Code/Python_Code/22.1.1_MatrixKeypad/MatrixKeypad.py
+++ b/Code/Python_Code/22.1.1_MatrixKeypad/MatrixKeypad.py
@@ -1,9 +1,8 @@
-#!/usr/bin/env python3
 ########################################################################
 # Filename    : MatrixKeypad.py
 # Description : obtain the key code of 4x4 Matrix Keypad
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2016/07/13
 ########################################################################
 import RPi.GPIO as GPIO
 import Keypad       #import module Keypad
@@ -22,11 +21,11 @@ def loop():
     while(True):
         key = keypad.getKey()       #obtain the state of keys
         if(key != keypad.NULL):     #if there is key pressed, print its key code.
-            print ("You Pressed Key : %c "%(key))
+            print "You Pressed Key : %c "%(key) 
             
 if __name__ == '__main__':     #Program start from here
-    print ("Program is starting ... ")
+    print "Program is starting ... "
     try:
         loop()
-    except KeyboardInterrupt:  #When 'Ctrl+C' is pressed, exit the program. 
-        GPIO.cleanup()
+    except KeyboardInterrupt:  #When 'Ctrl+C' is pressed, exit the program.      
+		GPIO.cleanup()  
diff --git a/Code/Python_Code/23.1.1_SenseLED/SenseLED.py b/Code/Python_Code/23.1.1_SenseLED/SenseLED.py
index 0444125..625f395 100644
--- a/Code/Python_Code/23.1.1_SenseLED/SenseLED.py
+++ b/Code/Python_Code/23.1.1_SenseLED/SenseLED.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : SenseLED.py
 # Description : Controlling an led by infrared Motion sensor.
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2016/06/12
 ########################################################################
 import RPi.GPIO as GPIO
 
@@ -11,7 +11,7 @@ ledPin = 12    # define the ledPin
 sensorPin = 11    # define the sensorPin
 
 def setup():
-	print ('Program is starting...')
+	print 'Program is starting...'
 	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
 	GPIO.setup(ledPin, GPIO.OUT)   # Set ledPin's mode is output
 	GPIO.setup(sensorPin, GPIO.IN)    # Set sensorPin's mode is input
@@ -20,10 +20,10 @@ def loop():
 	while True:
 		if GPIO.input(sensorPin)==GPIO.HIGH:
 			GPIO.output(ledPin,GPIO.HIGH)
-			print ('led on ...')
+			print 'led on ...'
 		else :
 			GPIO.output(ledPin,GPIO.LOW)
-			print ('led off ...')
+			print 'led off ...'		
 
 def destroy():
 	GPIO.cleanup()                     # Release resource
diff --git a/Code/Python_Code/24.1.1_UtrasonicRanging/UtrasonicRanging.py b/Code/Python_Code/24.1.1_UtrasonicRanging/UtrasonicRanging.py
index 0115c04..b7858fb 100644
--- a/Code/Python_Code/24.1.1_UtrasonicRanging/UtrasonicRanging.py
+++ b/Code/Python_Code/24.1.1_UtrasonicRanging/UtrasonicRanging.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : UltrasonicRanging.py
 # Description : Get distance from UltrasonicRanging.
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2016/07/15
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -34,7 +34,7 @@ def getSonar():     #get the measurement results of ultrasonic module,with unit:
     return distance
     
 def setup():
-    print ('Program is starting...')
+    print 'Program is starting...'
     GPIO.setmode(GPIO.BOARD)       #numbers GPIOs by physical location
     GPIO.setup(trigPin, GPIO.OUT)   #
     GPIO.setup(echoPin, GPIO.IN)    #
@@ -43,7 +43,7 @@ def loop():
     GPIO.setup(11,GPIO.IN)
     while(True):
         distance = getSonar()
-        print ("The distance is : %.2f cm"%(distance))
+        print "The distance is : %.2f cm"%(distance)
         time.sleep(1)
         
 if __name__ == '__main__':     #program start from here
diff --git a/Code/Python_Code/25.1.1_MPU6050/MPU6050.py b/Code/Python_Code/25.1.1_MPU6050/MPU6050.py
index a826113..4accc0e 100644
--- a/Code/Python_Code/25.1.1_MPU6050/MPU6050.py
+++ b/Code/Python_Code/25.1.1_MPU6050/MPU6050.py
@@ -138,7 +138,7 @@ class MPU6050:
         # Attempt to bypass adafruit lib
         #a_data_list = self.__mpu.bus.read_i2c_block_data(0x68, a_address, a_length)
         #print('data' + str(a_data_list))
-        for x in range(0, a_length):
+        for x in xrange(0, a_length):
             a_data_list[x] = self.__bus.read_byte_data(self.__dev_id,
                                                        a_address + x)
         return a_data_list
diff --git a/Code/Python_Code/25.1.1_MPU6050/MPU6050RAW.py b/Code/Python_Code/25.1.1_MPU6050/MPU6050RAW.py
index f426cf7..5dd5ae0 100644
--- a/Code/Python_Code/25.1.1_MPU6050/MPU6050RAW.py
+++ b/Code/Python_Code/25.1.1_MPU6050/MPU6050RAW.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 ########################################################################
 # Filename    : MPU6050RAW.py
 # Description : Read the Raw data of MPU6050.
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2016/07/18
 ########################################################################
 import MPU6050 
 import time
@@ -18,13 +18,13 @@ def loop():
     while(True):
         accel = mpu.get_acceleration()      #get accelerometer data
         gyro = mpu.get_rotation()           #get gyroscope data
-        print("a/g:%d\t%d\t%d\t%d\t%d\t%d "%(accel[0],accel[1],accel[2],gyro[0],gyro[1],gyro[2]))
-        print("a/g:%.2f g\t%.2f g\t%.2f g\t%.2f d/s\t%.2f d/s\t%.2f d/s"%(accel[0]/16384.0,accel[1]/16384.0,
-            accel[2]/16384.0,gyro[0]/131.0,gyro[1]/131.0,gyro[2]/131.0))
+        print"a/g:%d\t%d\t%d\t%d\t%d\t%d "%(accel[0],accel[1],accel[2],gyro[0],gyro[1],gyro[2])
+        print"a/g:%.2f g\t%.2f g\t%.2f g\t%.2f d/s\t%.2f d/s\t%.2f d/s"%(accel[0]/16384.0,accel[1]/16384.0,
+            accel[2]/16384.0,gyro[0]/131.0,gyro[1]/131.0,gyro[2]/131.0)
         time.sleep(0.1)
         
 if __name__ == '__main__':     # Program start from here
-    print("Program is starting ... ")
+    print"Program is starting ... "
     setup()
     try:
         loop()
diff --git a/Code/Python_Code/27.2.1_LightWater03/LightWater03.py b/Code/Python_Code/27.2.1_LightWater03/LightWater03.py
index b34f18b..07e6c66 100644
--- a/Code/Python_Code/27.2.1_LightWater03/LightWater03.py
+++ b/Code/Python_Code/27.2.1_LightWater03/LightWater03.py
@@ -1,9 +1,9 @@
-#!/usr/bin/env python3
+#!/usr/bin/env python
 #############################################################################
 # Filename    : LightWater03.py
 # Description : Control LED by 74HC595 on the DIY circuit board
 # Author      : freenove
-# modification: 2018/08/03
+# modification: 2016/08/16
 ########################################################################
 import RPi.GPIO as GPIO
 import time
@@ -59,7 +59,7 @@ def destroy():   # When 'Ctrl+C' is pressed, the function is executed.
 	GPIO.cleanup()
 
 if __name__ == '__main__': # Program starting from here 
-	print ('Program is starting...')
+	print 'Program is starting...' 
 	setup() 
 	try:
 		loop()