In this task, you're given an open-domain question. Your task is to provide an answer to the given question. There is only one unique answer for each question. Your answer should be short, and refer to an entity, date, number, etc. Do not put your answer in the context of a sentence.

Q: Who played gideon on once upon a time?

A: Giles Matthey
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Q: Journal of optics a pure and applied optics abbreviation?

A: J. Opt.
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Q: What episode of supergirl does she meet the flash?

A:
Worlds Finest
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