% perl -e 'print defined %URI:: ? "yes\n" : "no\n";'
no
% perl -e 'print defined %URI:: ? "yes\n" : "no\n"; require URI;'
no

##</code><code>##

% perl -e 'print defined %URI:: ? "yes\n" : "no\n";'
no
% perl -e 'print defined %URI:: ? "yes\n" : "no\n"; require URI;'
yes