When calling a Go function that returns multiple values that aren't errors, store it in a tuple

Because I was trying to wrap github.com/faiface/beep/vorbis so I can play audio, but the only useful function in that package returns (Streamer, Format, err), and because it returns too many values, Gopy refuses to add it in and I am seemingly stuck.
There should be no problem simply returning a tuple. There are also some methods that return multiple values none of which are errors. If Gopy finds a function that returns an error but doesn't do so using the last return value, it should throw a compile error, but I've never seen one of those.

首先跟踪 gopy 如何处理 Go 函数的返回值并生成相应的 Python 包装器，然后使用 github.com/faiface/beep/vorbis 重现该问题。完成标准是：多个非错误返回值以元组形式暴露，而 error 返回值不在最后的函数会产生编译错误。

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