* Add another rationale for this syntax
* Add missing escapes
* Improve wording as per comment from @stevendaprano
* added another sentence to clarify what `trio.run` actually does
In PEP-0637, in the example discussing setter notation, change the example from `__getitem__` to `__setitem__`, as the former appears to be a mistake in this context.
* PEP 637: more rationale for function call not being an option
* PEP 637 Commentary on the choice of tuple as sentinel when no index is specified
* Finalised explanation of rationale behind the empty tuple
* Clarified the proposed default hack
* Clarified asymmetry to functions
* Added review comments