# File lib/dm-core/resource.rb, line 37
    def self.included(model)
      model.extend Model
      model.extend ClassMethods if defined?(ClassMethods)
      model.const_set('Resource', self) unless model.const_defined?('Resource')
      extra_inclusions.each { |inclusion| model.send(:include, inclusion) }
      descendants << model
      class << model
        @_valid_model = false
        attr_reader :_valid_model
      end
    end