# File lib/chef/resource.rb, line 274
    def add_notification(action, resources, timing=:delayed)
      resources = [resources].flatten
      resources.each do |resource|
        case timing.to_s
        when 'delayed'
          notifies_delayed(action, resource)
        when 'immediate', 'immediately'
          notifies_immediately(action, resource)
        else
          raise ArgumentError,  "invalid timing: #{timing} for notifies(#{action}, #{resources.inspect}, #{timing}) resource #{self} "\
                                "Valid timings are: :delayed, :immediate, :immediately"
        end
      end

      true
    end