Go2将修改导出规则, 只有小写字母和"_"开头的不导出. 中文等不区分大小写的标识符默认导出.
> A solution that's been kicking around for a while:
> For Go 2 (can't do it before then): Change the definition to "lower case letters and _ are package-local; all else is exported". Then with non-cased languages, such as Japanese, we can write 日本語 for an exported name and _日本語 for a local name. This rule has no effect, relative to the Go 1 rule, with cased languages. They behave exactly the same.