It turns out that the return isn't absolutely necessary (except for efficiency) as the rest of the function can gracefully handle an illegal value for n.
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Going through diff between 6.2 and 6.3 I have noticed this:
Are you missing a return there?
Yes. It'll be in the next version.
It turns out that the return isn't absolutely necessary (except for efficiency) as the rest of the function can gracefully handle an illegal value for n.