I am not really certain how it would even be done in Nim. The for/while loop
doesn't have an innate label to `jmp` to. Shell uses `continue <n>` to jump to
the top of the Nth loop (for or while). And C just let's you arbitrarily define
labels to `jmp` to using `goto`. `break <label>` feels a little like solving 1
of the problems that regularly requires `goto`, or complicated flow control
variables w/ a chain of if/else checks.

It is curious that you can emulate `do { } while();` with `break <label>` as
well.