Alright, now we are getting somewhere. :)
Here's what you can do:

# !@{$array_ref} <-- Perl will complain about this if $array_ref is un
+defined
# $#{$array_ref} <-- but not this
if($#{$createdFiles->{$streamID}} == -1){
  print "Empty\n";
}
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--perlpelxer