included

# File actionmailer/lib/action_mailer/helpers.rb, line 3
    def self.included(base) #:nodoc:
      # Initialize the base module to aggregate its helpers.
      base.class_inheritable_accessor :master_helper_module
      base.master_helper_module = Module.new

      # Extend base with class methods to declare helpers.
      base.extend(ClassMethods)

      base.class_eval do
        # Wrap inherited to create a new master helper module for subclasses.
        class << self
          alias_method_chain :inherited, :helper
        end

        # Wrap initialize_template_class to extend new template class
        # instances with the master helper module.
        alias_method_chain :initialize_template_class, :helper
      end
    end