HELP with A02YYUW Waterproof Ultrasonic Sensor

   Start raspi-config: sudo raspi-config.
    Select option 3 - Interface Options.
    Select option P6 - Serial Port.
    At the prompt Would you like a login shell to be accessible over serial? answer 'No'
    At the prompt Would you like the serial port hardware to be enabled? answer 'Yes'
    Exit raspi-config and reboot the Pi for changes to take effect.

# -*- coding:utf-8 -*-

'''
  # demo_get_distance.py
  #
  # Connect board with raspberryPi.
  # Run this demo.
  #
  # Connect A02 to UART
  # get the distance value
  #
  # Copyright   [DFRobot](https://www.dfrobot.com), 2016
  # Copyright   GNU Lesser General Public License
  #
  # version  V1.0
  # date  2019-8-31
'''

import time

from DFRobot_RaspberryPi_A02YYUW import DFRobot_A02_Distance as Board

board = Board()

def print_distance(dis):
  if board.last_operate_status == board.STA_OK:
    print("Distance %d mm" %dis)
  elif board.last_operate_status == board.STA_ERR_CHECKSUM:
    print("ERROR")
  elif board.last_operate_status == board.STA_ERR_SERIAL:
    print("Serial open failed!")
  elif board.last_operate_status == board.STA_ERR_CHECK_OUT_LIMIT:
    print("Above the upper limit: %d" %dis)
  elif board.last_operate_status == board.STA_ERR_CHECK_LOW_LIMIT:
    print("Below the lower limit: %d" %dis)
  elif board.last_operate_status == board.STA_ERR_DATA:
    print("No data!")

if __name__ == "__main__":
  dis_min = 0   #Minimum ranging threshold: 0mm
  dis_max = 4500 #Highest ranging threshold: 4500mm
  board.set_dis_range(dis_min, dis_max)
  while True:
    distance = board.getDistance()
    print_distance(distance)
    time.sleep(0.3) #Delay time < 0.6s

Traceback (most recent call last):
  File "demo_get_distance.py", line 21, in <module>
    from DFRobot_RaspberryPi_A02YYUW import DFRobot_A02_Distance as Board
ImportError: No module named DFRobot_RaspberryPi_A02YYUW