FWIW ... where 'nothing' may be a valid value.
A SOPW today (26 Nov 14, US EST) included a use info; which made me curious ...and which seems to lead to an ID on paco
perldoc info
NAME
perlinfo - a command-line frontend to HTML::Perlinfo
# [irrelevant details -- for the purposes of this post -- edite
+d out]
EXAMPLES
perlinfo -i
'Saved file perlinfo.html'
perlinfo -i /home/paco/www/perl-info.html
'Saved file /home/paco/www/perl-info.html'
COPYRIGHT
Copyright (c) 2009 by Mike Accardo
...
Quis custodiet ipsos custodes. Juvenal, Satires