DB<1> w $t
  DB<2> c
Watchpoint 0:   $t changed:
    old value:  ''
    new value:  '14'
main::(dbt.pl:4):       print "$t\n";
  DB<2> W $t
  DB<3> $z=\$t
  DB<4> w $$z
  DB<5> c
14
Watchpoint 0:   $$z changed:
    old value:  '14'
    new value:  '15'
main::(dbt.pl:6):       print "$t\n";
  DB<5> c
15
42
15
Watchpoint 0:   $$z changed:
    old value:  '15'
    new value:  ''
Debugged program terminated.