Interfacing RPI and distance sensor

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BCM)
GPIO_TRIG = 11
GPIO_ECHO = 18
GPIO.setup(GPIO_TRIG, GPIO.OUT)
GPIO.setup(GPIO_ECHO, GPIO.IN)

GPIO.output(GPIO_TRIG, GPIO.LOW)
time.sleep(2)

GPIO.output(GPIO_TRIG, GPIO.HIGH)
time.sleep(0.00001)
GPIO.output(GPIO_TRIG, GPIO.LOW)

while GPIO.input(GPIO_ECHO) == 0:
    start_time = time.time()

while GPIO.input(GPIO_ECHO) == 1:
    bounce_back_time = time.time()

pulse_duration = bounce_back_time - start_time
distance = round(pulse_duration * 17150, 2)
print(f"Distance: {distance}cm")

GPIO.cleanup()