I knew about variadic functions, and the “…” syntax, but I’d assumed that was limited to the function declaration. When I tried to pass a slice of arguments as the final parameter of a call to a variadic function, I got errors. The answer is of course in the spec, but I didn’t find it quickly:

v := foo(bar, baz...)

So “…” shows up again. Here’s the relevant section of the spec:

Passing arguments to … parameters