In reading Learning More Perl, I need the following code explained: 
unless ($turn) {
  print "on course.\n";
  return;
}

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How (and for what) is turn being evaluated? I can't find much on the until statement, except that it evaluates for non-truth.

janitored by ybiC: Retitle from "Until loop", add balanced <code> tags

In reply to unless ($turn){...} evaluates $turn for what? by mhearse

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