get plus (+) working

alas, new integer is not created yet

lib/parfait/integer.rb

@@ -19,6 +19,11 @@ module Parfait
     def self.integer_index
       3 # 1 type, 2 next_i
     end
+
+    def get_internal_word( index )
+      return super(index) unless index == Integer.integer_index
+      return @value
+    end
     # :integer?, :odd?, :even?, :upto, :downto, :times, :succ, :next, :pred, :chr, :ord, :to_i, :to_int, :floor,
     # :ceil, :truncate, :round, :gcd, :lcm, :gcdlcm, :numerator, :denominator, :to_r, :rationalize,
     # :singleton_method_added, :coerce, :i, :+@, :-@, :fdiv, :div, :divmod, :%, :modulo, :remainder, :abs, :magnitude,