use include so we can test with is_a

using the well documented included/extend trick

lib/register/assembler.rb

@@ -168,7 +168,7 @@ module Register
       end
       #puts "layout length=#{layout.get_length.to_s(16)} mem_len=#{layout.word_length.to_s(16)}"
       l = layout.get_length
-      if( object.is_a? Parfait::List)
+      if( object.is_a? Parfait::Indexed)
         object.each do |inst|
           write_ref_for(inst)
         end

lib/register/collector.rb

@@ -27,7 +27,7 @@ module Register
         inst = object.get_instance_variable name
         keep(inst , depth + 1)
       end
-      if object.is_a? Parfait::List
+      if object.is_a? Parfait::Indexed
         object.each do |item|
           #puts "Keep item "
           keep(item , depth + 1)