DIP 1017--Add Bottom Type--Community Review Round 1

[Uknown]

I would like to point out that C++ does this with attributes 
instead[0]. If this was an attribute instead (like `@noreturn`), 
it would simplify interfacing with C++. It would also avoid the 
breaking change.

[0]: eel.is/c++draft/DCL.attral.noreturn