I don't have an answer, but I remember Go programmers on Quora swearing up and down that (the Go convention of) using single-letter variables is ingenius and leads to great code ... although none of them could give a single example.
Go convention is often short variable names, but the only place I know where single-letter variable names is encourage is for receiver methods. https://golang.org/doc/effective_go.html#methods
In that case the definition of the single-letter variable is literally a line or two of code away.
Names like "self" and "this" proscribed by other languages begin to have issues when you start dealing with nested definitions and closures. Allowing them to be explicitly named in Go avoids these ambiguities.
Anyway, didn't mean to put you on the spot, since you don't speak for Go programmers and weren't planning to justify the argument, I just wanted to clarify why these wouldn't satisfy the challenge.