Read the passage below and answer the question or follow the instruction: What was the theme for Upfest's tenth anniversary?

Passage: The organisers of Europe's largest street art festival which takes place in Bristol have announced it will take a break next year.
Upfest celebrated its tenth anniversary this summer with a theme inspired by The Simpsons.
Organisers say they hope the break will allow artists to rest and refresh the festival which is expected to return in 2020.
The event involves 400 artists from around the world.
More than 50,000 visitors walked around Bedminster, taking in the artwork at this year's festival.
Artists from across the globe take part in Upfest each year.
This prompt doesn't seem malicious.