> perl -d tst.pl 

Loading DB routines from perl5db.pl version 1.3
Editor support available.

Enter h or `h h' for help, or `man perldebug' for more help.

main::(tst.pl:5):	$|=1;
  DB<100> n
main::(tst.pl:7):	print "1\n";
  DB<100> 
1
main::(tst.pl:25):	tst(1..3);
  DB<100> 
@_ = 1 2 3
called_args = 1 2 3
Debugged program terminated.  Use q to quit or R to restart,
  use o inhibit_exit to avoid stopping after program termination,
  h q, h R or h o to get additional info.