text: #!/usr/bin/python
  #!/usr/bin/python3
  # Copyright 2021 Google LLC
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #      http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  import RPi.GPIO as GPIO
  import time
   
  #GPIO SETUP
  channel = 21
  GPIO.setmode(GPIO.BCM)
  GPIO.setup(channel, GPIO.IN)
   
  def callback(channel):
          if GPIO.input(channel):
                  print "Water Detected!"
          else:
                  print "Water Detected!"
   
  GPIO.add_event_detect(channel, GPIO.BOTH, bouncetime=300)  # let us know when the pin goes HIGH or LOW
  GPIO.add_event_callback(channel, callback)  # assign function to GPIO PIN, Run function on change
   
  # infinite loop
  while True:
          time.sleep(1)