$ irb
irb(main):001:0> require 'digest/md5'
=> true
irb(main):002:0> puts Digest::MD5.hexdigest("password")
5f4dcc3b5aa765d61d8327deb882cf99
=> nil
$ irb
irb(main):001:0> require 'digest/md5'
=> true
irb(main):002:0> puts Digest::MD5.hexdigest("password")
5f4dcc3b5aa765d61d8327deb882cf99
=> nil