D:\Users\RolfLangsdorf>perl -de0

Loading DB routines from perl5db.pl version 1.37
Editor support available.

Enter h or 'h h' for help, or 'perldoc perldebug' for more help.

main::(-e:1):   0

  DB<1> x [!!0,!!1]
0  ARRAY(0x28d1a8)
   0  ''
   1  1

  DB<2>

##</code><code>##

  DB<1> use constant {TRUE => !!1, FALSE=> !!0}


  DB<2> x [TRUE,FALSE]
0  ARRAY(0x4c6170)
   0  1
   1  ''