def initialize_constants!
      @initialize_constants ||= begin
        class_const = options[:class] || @name.to_s.camelize
        class_const = class_const.constantize if class_const.is_a?(String)
        options[:class] = class_const

        if options[:builder]
          options[:builder] = options[:builder].constantize if options[:builder].is_a?(String)
        end

        true
      end
      
      unless Mutations.cache_constants?
        options[:class] = options[:class].to_s.constantize if options[:class]
        options[:builder] = options[:builder].to_s.constantize if options[:builder]
      end
    end
def initialize_constants!
      @initialize_constants ||= begin
        class_const = options[:class] || @name.to_s.camelize
        class_const = class_const.constantize if class_const.is_a?(String)
        options[:class] = class_const

        if options[:builder]
          options[:builder] = options[:builder].constantize if options[:builder].is_a?(String)
        end

        true
      end
      
      unless Mutations.cache_constants?
        options[:class] = options[:class].to_s.constantize if options[:class]
        options[:builder] = options[:builder].to_s.constantize if options[:builder]
      end
    end
Initialize the model class and builder