code: def optimize(image, fmt='jpeg', quality=80):
      
      from io import BytesIO
  
      if IMAGE_OPTIMIZATION_CMD and is_tool(IMAGE_OPTIMIZATION_CMD):
          image_buffer = BytesIO()
          image.save(image_buffer, format=fmt, quality=quality)
          image_buffer.seek(0)  # If you don't reset the file pointer, the read command returns an empty string
          p1 = subprocess.Popen(IMAGE_OPTIMIZATION_CMD, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
          output_optim, output_err = p1.communicate(image_buffer.read())
          if not output_optim:
              logger.debug("No image buffer received from IMAGE_OPTIMIZATION_CMD")
              logger.debug("output_err: {0}".format(output_err))
              return image
          im = Image.open(BytesIO(output_optim))
          return im
      else:
          return image
docs: Optimize the image if the IMAGE_OPTIMIZATION_CMD is set.
  
      IMAGE_OPTIMIZATION_CMD must accept piped input