def attributes(*attributes)
      attributes.each do |attr|
        raise ArgumentError.new("You cannot use #{attr} as an attribute name since it is a reserved method name of Xapian::Document") if reserved_method_name?(attr)
        @attributes_hash[attr] = {}
        @type_map[attr] = :string
        self.index attr
      end
    end
def attributes(*attributes)
      attributes.each do |attr|
        raise ArgumentError.new("You cannot use #{attr} as an attribute name since it is a reserved method name of Xapian::Document") if reserved_method_name?(attr)
        @attributes_hash[attr] = {}
        @type_map[attr] = :string
        self.index attr
      end
    end
Add a list of attributes to the blueprint. Attributes will be stored in the xapian documents ans
 can be accessed from a search result.
 @param [Array] attributes An array of method names that deliver the values for the attributes