Task: Question Answering
Input (English): passage: In the United States, although the legality of headlight flashing varies from state to state, a federal court ruled that flashing headlights was a constitutionally protected form of speech, issuing an injunction prohibiting a police department from citing or prosecuting drivers who flash their lights to warn of radar and speed traps.
 question: is it illegal to flash lights to warn of police?
Output (English): No