Description:
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on most platforms, it won't make a difference, but where it actually does, the implicit `rt` mode of `r` sure is a portability hazard when not thinking about it, thus i suggest making the default mode `rb`, thus being "portable by default". and ofc, when you take the time to think about rb vs rt, and you decide to depend on rt, you can just set the `rt` mode manually. migrating codebases depending on the current default, is trivial, and this change would make it easier to write portable code.