You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.
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Question: Category: HE WAS IN THAT? 
Clue: As a child Robert Blake played a Mexican boy in this Bogart classic directed by John Huston

Answer: "the treasure of the sierra madre"


Question: Category: BRIT LIT 
Clue: His 1915 novel "The Rainbow" was declared obscene; so was his 1928 novel

Answer: d.h. lawrence


Question: Category: 4.O 
Clue: In baby talk it's the sound of a steam locomotive

Answer:
choo-choo