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sure if I have a preference if they're a equivalent, but is this functionally different from:\r\n```\r\ntry:\r\n    hash(field)\r\nexcept:\r\n    raise ValueError(...)\r\n```\r\n?","created_at":"2015-06-02T13:13:25Z","updated_at":"2015-06-02T13:13:25Z","html_url":"https://github.com/quantopian/zipline/pull/591#discussion_r31520260","pull_request_url":"https://api.github.com/repos/quantopian/zipline/pulls/591","_links":{"self":{"href":"https://api.github.com/repos/quantopian/zipline/pulls/comments/31520260"},"html":{"href":"https://github.com/quantopian/zipline/pull/591#discussion_r31520260"},"pull_request":{"href":"https://api.github.com/repos/quantopian/zipline/pulls/591"}}},"pull_request":{"url":"https://api.github.com/repos/quantopian/zipline/pulls/591","id":36538359,"html_url":"https://github.com/quantopian/zipline/pull/591","diff_url":"https://github.com/quantopian/zipline/pull/591.diff","patch_url":"https://github.com/quantopian/zipline/pull/591.patch","issue_url":"https://api.github.com/repos/quantopian/zipline/issues/591","number":591,"state":"open","locked":false,"title":"history 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