Write the next sentence in this paragraph:

How to hang lights on a christmas tree
Plug the lights in to make sure that each bulb works.
If a few don't, try tightening them-they may not be broken after all. Once you're confident they work, unravel them.
This way you don't spend minutes unraveling what you don't use. Spend a couple of minutes tinkering with them, and then if they still don't work, throw them out.