line 1. we create the class, inheriting from pygame.
line 2. we "__init__" like usual.  
 Note: "__init__" has 2 underscores
line 3. we call the pygame "__init__"
​line 4. we load the image
  Note: I don't load it in the class because if we had 40 pipes it would be too slow
line 5. we make a rect according to the image
lines 6&7. we create the x and y
​line 10. I make a method called update
  Note: its name is important because it it one of the only methods that you can call for all the sprites in a group.
line 11. we display the image
line 12. we create the rect(x pos, y pos, width, height)
   Note: using self.rect = Rect (...) for the updated image is important for collision detection 
line 15. we load the pipe image.
line 16: we create a sprite group
line 18. we add members to the sprite group
line 20. we call the update method for all the sprites in the group