introduce constant class and add block to compile signature(wip, work in progress)

lib/ast/while_expression.rb

@@ -13,6 +13,14 @@ module Ast
     def attributes
       [:condition, :body]
     end
+    def compile context , into
+      cond_val = condition.compile(context , into)
+      #set up branches for bodies
+      body.each do |part|
+        part.compile(context , into )
+      end
+      return cond_val
+    end
   end