First let's call it a snake cozy. It can't wear a sweater for warmth because snakes are cold blooded and don't generate their own body heat. If she's using it to retain heat its already absorbed ok...but it can't crawl around while wearing it because the "sweater" renders to zero it's ability to move. It will slither into the cozy and out of it but it can't slither around its environment wearing it. It might like the sweater for hiding in.

Awesome how the sweater matches its eyes! I'm sure the snake feels much better now that it's coordinated.