C:\>perl -e"print require CGI;"
1
C:\>perl -e"print require CGIshamalamadingdong;"
Can't locate CGIshamalamadingdong.pm in @INC 

##</code><code>##

$ perl -E '$ok = eval "require CGI" ? 1:0; say $ok'
1
$ perl -E '$ok = eval "require CGIshamalamadingdong" ? 1:0; say $ok'
0