code: def attributes(&block)
        raise ArgumentError, "You should provide block" unless block_given?
  
        attributes = Morf::AttributesParser.parse(&block)
        self.class_variable_set(:@@attributes, attributes)
      end
docs: Defines casting rules
   @example
    attributes do
      string   :first_name
      string   :last_name
      integer  :age, optional: true
    end