fix fibo with new syntax. certainly works for operators, but not everything

lib/arm/compare_instruction.rb

@@ -88,7 +88,7 @@ module Arm
       io.write_uint32 val
     end
     def shift val , by
-      raise "Not integer #{val}:#{val.class}" unless val.is_a? Fixnum
+      raise "Not integer #{val}:#{val.class} #{inspect}" unless val.is_a? Fixnum
       val << by
     end
   end