Sure. Suppose noob comes up to his screen with a program that isn't working right:

#!/usr/bin/perl

for ($i=0,$i<=5,$i++)
{ 
    print "FOO\n"; 
}
[download]

which prints:

FOO
FOO
FOO
[download]

no matter what he does. (classic newbie mistake that used to bug me when I was doing C :) He checks a box that says "output is incorrect."

Our critter will extract the for() loop from his code, and wrap it in :

eval 
{
  for (i=0,$i<=5,$i++)
  { 
      print "FOO\n"; 
  }
};
print "'$@'";
[download]

This tells our critter that the code did execute. It's next step is to examine node replies for similar code fragments. Pretty soon (!), it discovers that a for() loop should have ';' instead of ',' as iterator separators, and hands back the code:

#!/usr/bin/perl
for ($i=0;$i<=5;$i++)
{ 
    print "FOO\n"; 
}
[download]

A further refinement would have it make a scope declaration pass, and hand back:

#!/usr/bin/perl
use strict;
use warnings;
for (my $i=0;$i<=5;$i++)
{ 
    print "FOO\n"; 
}
[download]