Two 7-segment LEDs with only one shift-register and transistor multiplexer

#!/usr/bin/env python
import RPi.GPIO as GPIO
import time
import random

SDI = 11
RCLK = 12
SRCLK = 13

LedPin1 = 15
LedPin2 = 16 

holdt=0.001

segCode = [0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71,0x80]

def print_msg():
 print 'Program is running...'
 print 'Please press Ctrl+C to end the program...'

def setup():
 GPIO.setmode(GPIO.BOARD)
 #setup pins
 GPIO.setup(SDI, GPIO.OUT)
 GPIO.setup(RCLK, GPIO.OUT)
 GPIO.setup(SRCLK, GPIO.OUT)
 #set default state
 GPIO.output(SDI, GPIO.LOW)
 GPIO.output(RCLK, GPIO.LOW)
 GPIO.output(SRCLK, GPIO.LOW)
 GPIO.setup(LedPin1, GPIO.OUT)
 GPIO.output(LedPin1, GPIO.LOW)
 GPIO.setup(LedPin2, GPIO.OUT)
 GPIO.output(LedPin2, GPIO.LOW) 

def hc595_shift(dat,lcd):
 #push 8 bits into the register
 GPIO.output(LedPin1, GPIO.LOW)
 GPIO.output(LedPin2, GPIO.LOW)
 for bit in range(0, 8):
     GPIO.output(SDI, 0x80 & (dat << bit)) #shift the bit and push it
     GPIO.output(SRCLK, GPIO.HIGH) # set the clk
     time.sleep(0.001)
     GPIO.output(SRCLK, GPIO.LOW) # set to low (initial state)
 GPIO.output(RCLK, GPIO.HIGH) #init output
 time.sleep(0.001)
 if lcd == 1:
     GPIO.output(LedPin1, GPIO.HIGH)
     GPIO.output(LedPin2, GPIO.LOW)
 else:
     GPIO.output(LedPin1, GPIO.LOW)
     GPIO.output(LedPin2, GPIO.HIGH)
 GPIO.output(RCLK, GPIO.LOW) # output

def loop():
 while True:
   for i in range(0,6):
        i = random.randint(1,100)
        x = divmod(i,10)
        for i in range(0,25):
            for j in range(0,2):
                hc595_shift(segCode[x[j]],j+1)
                time.sleep(holdt)

def destroy():
 GPIO.output(LedPin1, GPIO.LOW)
 GPIO.output(LedPin2, GPIO.LOW)
 GPIO.cleanup()

if __name__ == '__main__':
 print_msg()
 setup()
 try:
        loop()
 except KeyboardInterrupt:
        destroy()

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