Note that I said 'trivially'. The structure and meaning of an 'unless' construction is the same as 'if', adding or removing only a negation. Using 'while' and

Note that I said 'trivially'. The structure and meaning of an 'unless' construction is the same as 'if', adding or removing only a negation. Using 'while' and a jump to construct a loop is much more expressively distant from 'for'.