$ ack -cl MIME::Base64 
lib/Net/SSH/Perl/Util/Hosts.pm:5
lib/Net/SSH/Perl/Key/RSA.pm:1
lib/Net/SSH/Perl/Key/DSA.pm:1
lib/Net/SSH/Perl/Key.pm:1
lib/Crypt/DSA/Signature.pm:2
lib/Crypt/DSA/Key/SSH2.pm:1
lib/Bundle/LWP.pm:1
lib/WWW/Mechanize/FAQ.pod:2
lib/HTTP/Message.pm:6
lib/HTTP/Headers.pm:3
lib/HTTP/Response.pm:3
lib/HTTP/Request/Common.pm:2
lib/URI/data.pm:1
lib/i486-linux-gnu-thread-multi/Digest/SHA.pm:2
lib/Module/CoreList.pm:18
lib/LWP/Authen/Basic.pm:2
lib/LWP/Authen/Ntlm.pm:1
lib/Convert/ASCII/Armour.pm:3
lib/Convert/PEM.pm:1
lib/Data/Dump.pm:4