% perl -MDevel::Peek -wle '
  $x="\x{100}"; Dump($x);
  chop $x;      Dump($x);
  $y = "foo";   Dump($y);
  $y .= $x;     Dump($y)
' 2>&1 | grep FLAGS
  FLAGS = (POK,IsCOW,pPOK,UTF8)
  FLAGS = (POK,pPOK,UTF8)
  FLAGS = (POK,IsCOW,pPOK)
  FLAGS = (POK,pPOK,UTF8)
%