foreach / mutating iterator - How to do this?

[Robert M. Münch via Digitalmars-d-learn]

I have two foreach loops where the inner should change the iterator 
(append new entries) of the outer.

foreach(a, candidates) {
        foreach(b, a) {
                if(...) candidates ~= additionalCandidate;
        }
}
The foreach docs state that the collection must not change during iteration.

So, how to best handle such a situation then? Using a plain for loop?

--
Robert M. Münch
http://www.saphirion.com
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