$ perl -e'
   use Devel::Peek qw( Dump );
   my $s = "a\N{U+2660}";
   Dump($s);
   my $ss = substr($s, 0, 1);
   Dump($ss);
'
SV = PV(0x7fffd3496ca0) at 0x7fffd34c5a88
  REFCNT = 1
  FLAGS = (POK,IsCOW,pPOK,UTF8)
  PV = 0x7fffd34c33a0 "a\342\231\240"\0 [UTF8 "a\x{2660}"]
  CUR = 4
  LEN = 10
  COW_REFCNT = 1
SV = PV(0x7fffd3496d30) at 0x7fffd34c5ad0
  REFCNT = 1
  FLAGS = (POK,pPOK,UTF8)
  PV = 0x7fffd34ad050 "a"\0 [UTF8 "a"]
  CUR = 1
  LEN = 10