embedding-shape parent
For me it's interesting because global variable declarations haven't been needed before, so why now? Also, I'm not sure `global` was reserved before, but now it seems to be.
The point now is so that if you use a `global` statement in your code, Lua will now error on misspellings of local variables when compiling, rather than defaulting to treat them as globals.
lua does not preserve compatibility between minor versions. As such they don't need to reserve words for future use.