This module lets you add debugging instructions which look
like comments and do nothing unless you 'use' this module.

	use Devel::StealthDebug;

	my $foo = 0;
	# ... Several processing on $foo

	my $bar = 1 / $foo;    #!assert($foo != 0)!

	my %myhash;                    #!watch(%myhash)!

	sub func1 {                    #!emit(Entering func1)!
	#...
	}