DB<137> use List::Util qw/pairkeys pairvalues/

  DB<138> x pairkeys  split /(?<=(.))(?!\1)/, $in
0  'Z'
1  'BBB'
2  'C'
3  'ZZ'
  DB<139> x pairvalues  split /(?<=(.))(?!\1)/, $in
0  'Z'
1  'B'
2  'C'
3  'Z'
  DB<140>