sub eteb {   
  my $data = shift;
  my $orig = $data;
  Dump($data);
  my @array = extract_multiple(
    $data,   
    [ sub{extract_tagged($_[0], 'a', 'b', undef,)}, ],
    undef,
    1
  );
  Dump($data);
  $data = $data."";
  Dump($data);
  print "data='$data'\n";                                                                               
  display('eteb1', @array);
  @array = extract_multiple(
    $data,
    [ sub{extract_bracketed($_[0], '()')}, ],
    undef,
    1
  );
  display('eteb2', @array);
} 
<c>
<p>And sure enough, some stuff inside changed:</p>
<c>
$ perl 1005372.pl
et:a)(b
eb:(a)(b)
SV = PV(0x8458478) at 0x84fe160
  REFCNT = 1
  FLAGS = (PADMY,POK,pPOK)
  PV = 0x83c47b8 "(a)(b)"\0
  CUR = 6
  LEN = 8
SV = PVMG(0x83ef3a8) at 0x84fe160
  REFCNT = 7
  FLAGS = (PADMY,SMG,POK,pPOK)
  IV = 0
  NV = 0
  PV = 0x83c47b8 "(a)(b)"\0
  CUR = 6
  LEN = 8
  MAGIC = 0x83c2ec0
    MG_VIRTUAL = &PL_vtbl_mglob
    MG_TYPE = PERL_MAGIC_regex_global(g)
    MG_LEN = 5
SV = PVMG(0x83ef3a8) at 0x84fe160
  REFCNT = 7
  FLAGS = (PADMY,SMG,POK,pPOK)
  IV = 0
  NV = 0
  PV = 0x83c47b8 "(a)(b)"\0
  CUR = 6
  LEN = 8
  MAGIC = 0x83c2ec0
    MG_VIRTUAL = &PL_vtbl_mglob
    MG_TYPE = PERL_MAGIC_regex_global(g)
    MG_LEN = -1
data='(a)(b)'
eteb1:a)(b
eteb2:(a)(b)