explore parsing standard financial reports like 10K/10Q

[simonmichael]

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From #hledger chat today. As part of using hledger to analyse public financial reports, it seems like a useful step would be to develop and document how to import data from a few of the most common public reports. Eg the yearly https://en.wikipedia.org/wiki/Form_10-K report required by the US SEC. First step would be to research typical data formats. If there's a standard CSV format, perhaps we can read that with suitable rules (to get a journal with summary transactions).