> This is useful, but two totally different functions with the same name distinguished only by the presence, not even the value of an unused argument.
The sentinel argument is not unused.
> Where else does anything like this exist in the language?
In the narrow sense of “in the language” (builtins only), it's unique. There may be other examples in stdlib. That aside, functions that do a descriptively similar thing (i.e.,“build an iterator”) but where the details of how they do it differ significantly by aritt aren't weird among programming languages generally; don't see why it would be particularly problematic.
