setting up switch to display information on matrix led

switch.py

import RPi.GPIO as GPIO
import time
import os
import csv

GPIO.setmode(GPIO.BCM)


#pin bawah skali, seblah ground
GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_UP)


while True:

#    with open('/media/usb1/operation_logs.csv', 'rb') as csvfile:
#        reader = csv.reader(csvfile)
#        for row in reader:
#            print(row)


    input_state = GPIO.input(21)
    if input_state == False:
        print("button pressed")
#       os.system('python /home/pi/Desktop/switch/matrix_led.py')
        time.sleep(0.2)