Today, I was walking down the same city street, and noticed how clean it was. Someone was standing there looking smug. He had a cardboard box with a handle and a lot of airholes. I couldn't tell what was inside box, but he noticed that I was looking at him.
"I've trained these moths to pick up trash for me," he said, without greeting, "But only on this single city block."
I was astounded, but a few minutes later, when the man was distracted, I looked inside the cardboard box.... to find that the box was empty.