# File lib/mongoid/observer.rb, line 154
    def define_callbacks(klass)
      tap do |observer|
        observer_name = observer.class.name.underscore.gsub('/', '__')
        Mongoid::Callbacks::CALLBACKS.each do |callback|
          next unless respond_to?(callback)
          callback_meth = "_notify_#{observer_name}_for_#{callback}""_notify_#{observer_name}_for_#{callback}"
          unless klass.respond_to?(callback_meth)
            klass.send(:define_method, callback_meth) do |&block|
              observer.send(callback, self, &block)
            end
            klass.send(callback, callback_meth)
          end
        end
      end
    end