Fix diary_env.example.rb

Signed-off-by: Sergey Bogdanov <sergey.bogdanov@oktetlabs.ru>

diary_env.example.rb

@@ -5,6 +5,7 @@
 # Class DiaryEnv for Diary Management Application.
 #
 
+require 'singleton'
 require_relative 'ldap_record'
 require_relative 'diary_datamapper'
 
@@ -51,7 +52,7 @@ class DiaryEnv
         @director = []
         DataMapper.database.query(cmd, as: :hash, symbolize_keys: false).each do |q|
             raise "'Director' table is not filled" unless
-                q and name = q.fetch['nick']
+                q and name = q.fetch('nick')
             @director.push(Person.new(name))
         end
     end