text: import io
  import random
  import picamerax
  from PIL import Image
  
  prior_image = None
  
  def detect_motion(camera):
      global prior_image
      stream = io.BytesIO()
      camera.capture(stream, format='jpeg', use_video_port=True)
      stream.seek(0)
      if prior_image is None:
          prior_image = Image.open(stream)
          return False
      else:
          current_image = Image.open(stream)
          # Compare current_image to prior_image to detect motion. This is
          # left as an exercise for the reader!
          result = random.randint(0, 10) == 0
          # Once motion detection is done, make the prior image the current
          prior_image = current_image
          return result
  
  with picamerax.PiCamera() as camera:
      camera.resolution = (1280, 720)
      stream = picamerax.PiCameraCircularIO(camera, seconds=10)
      camera.start_recording(stream, format='h264')
      try:
          while True:
              camera.wait_recording(1)
              if detect_motion(camera):
                  print('Motion detected!')
                  # As soon as we detect motion, split the recording to
                  # record the frames "after" motion
                  camera.split_recording('after.h264')
                  # Write the 10 seconds "before" motion to disk as well
                  stream.copy_to('before.h264', seconds=10)
                  stream.clear()
                  # Wait until motion is no longer detected, then split
                  # recording back to the in-memory circular buffer
                  while detect_motion(camera):
                      camera.wait_recording(1)
                  print('Motion stopped!')
                  camera.split_recording(stream)
      finally:
          camera.stop_recording()
  