Found some odd behaviour in functional?
Does it crash? Give you the wrong answer? Take your lunch money?
If it did any of these things, or anything else you don't like, please submit a report.
Even if the bug is as simple as "the C version does X, but the pure-python version does Y", let us know.
So, if you think you may know something that we don't, check the "Bugs We Know About" section; if your bug isn't in there, keep on reading.