The actual code that generated my query was considerably more complicated. In a forlorn attempt to make, what I knew was a easy question, more readable I created a simple test case. Sorry!
Thanks to arturo I now know its a hash slice (having read 5 books that mention it - including your llama you'd have thought I'd have remembered but its not a construct I would normally use).

Personally I don't have a problem with homework questions. I don't see any moral case at all. After all whats the difference between an ignorant student and an ignorant contractor who's bluffed his way into a job? By your rationale you'd freely help one but not the other.

If I didn't want to answer a question I'd just ignore it or perhaps suggest to the 'students' another educational theory...

s/HOMEWORK/FO&FO/

FO&FO = F*** Off and Find Out

"We are all prompted by the same motives, all deceived by the same fallacies, all animated by hope, obstructed by danger, entangled by desire, and seduced by pleasure." - Samuel Johnson