code: def reveal(input_image: Union[str, IO[bytes]]):
      
      img = tools.open_image(input_image)
      width, height = img.size
      message = ""
      index = 0
      for row in range(height):
          for col in range(width):
              r, g, b = img.getpixel((col, row))
              # First pixel r value is length of message
              if row == 0 and col == 0:
                  message_length = r
              elif index <= message_length:
                  message += chr(r)
              index += 1
      img.close()
      return message
docs: Find a message in an image.
  
      Check the red portion of an pixel (r, g, b) tuple for
      hidden message characters (ASCII values).
      The red value of the first pixel is used for message_length of string.