import RPi.GPIO as GPIO
import time
from smbus import SMBus
ard_addr = bytearray([0x04, 0x05, 0x06, 0x07, 0x09, 0x0a, 0x0b, 0x0c])
led_addr_LSB = bytearray([0x66, 0xb6, 0xbe, 0xe0, 0xe6, 0xee, 0x3e, 0x1a])
bus = SMBus(1) # indicates /dev/ic2-1



LSBFIRST = 1
MSBFIRST = 2

dataPin   = 11    #DS Pin of 74HC595(Pin14)
latchPin  = 13    #ST_CP Pin of 74HC595(Pin12)
clockPin = 15    #CH_CP Pin of 74HC595(Pin11)

def setup():
    GPIO.setwarnings(False)
    GPIO.setmode(GPIO.BOARD)
    GPIO.setup(dataPin, GPIO.OUT)
    GPIO.setup(latchPin, GPIO.OUT)
    GPIO.setup(clockPin, GPIO.OUT)
  
def shiftOut(dPin,cPin,order,val):
    for i in range(0,8):
        GPIO.output(cPin,GPIO.LOW);
        if(order == LSBFIRST):
            GPIO.output(dPin,(0x01&(val>>i)==0x01) and GPIO.HIGH or GPIO.LOW)
        elif(order == MSBFIRST):
            GPIO.output(dPin,(0x80&(val<<i)==0x80) and GPIO.HIGH or GPIO.LOW)
        GPIO.output(cPin,GPIO.HIGH);  

def loop():
    cnt = 0
    while True:
        cnt = 0
        GPIO.output(latchPin,GPIO.LOW)
        shiftOut(dataPin,clockPin,LSBFIRST,0x00)
        GPIO.output(latchPin,GPIO.HIGH)
        time.sleep(0.1)      
        while cnt < 8:
            
            # turn on LED 13
            bus.write_byte(ard_addr[cnt], 0x1) #switch it on        
            GPIO.output(latchPin,GPIO.LOW)
            shiftOut(dataPin,clockPin,LSBFIRST,led_addr_LSB[cnt])
            GPIO.output(latchPin,GPIO.HIGH)
            time.sleep(2) 
            # turn off LED 13
            bus.write_byte(ard_addr[cnt], 0x0) #switch it off
            time.sleep(2)                    
            # blank 
            GPIO.output(latchPin,GPIO.LOW)
            shiftOut(dataPin,clockPin,LSBFIRST,0x00)
            GPIO.output(latchPin,GPIO.HIGH)
            time.sleep(0.1)
            cnt += 1

     
def destroy(): 
    GPIO.cleanup()

if __name__ == '__main__':
    print ('Program is starting...' )
    setup() 
    try:
        loop()  
    except KeyboardInterrupt:  
        destroy()   

I combined the 7 Segment display of the Raspberry Pi and the 8 Arduino LED 13 code. I tightened up the code. This one uses the LSB logic table below.