'continue' while s/$EN$ES$EN/$EN$EN$EN/g;
      'continue' while s/([$EN$AN])$CS\1/$1$1$1/g;
'continue' while: repeat to catch overlaps (syntax very
    Perlish)[...]: Character class, any of the contained
  characters\1, $1: Back references caught by
    ()14 of 15  |