diff --git a/lib/sof/array.rb b/lib/sof/array.rb
index 3c896923..318eea06 100644
--- a/lib/sof/array.rb
+++ b/lib/sof/array.rb
@@ -1,6 +1,6 @@
 Array.class_eval do
   def to_sof_node(members , level)
-    node = Sof::ChildrenNode.new(nil)
+    node = Sof::NodeList.new()
     each do |object|
       node.add members.to_sof_node( object )
     end
diff --git a/lib/sof/hash.rb b/lib/sof/hash.rb
index 38d329a6..6ab77b59 100644
--- a/lib/sof/hash.rb
+++ b/lib/sof/hash.rb
@@ -1,13 +1,9 @@
 Hash.class_eval do
   def to_sof_node(members , level)
-    each_with_index do |pair , i|
-      key , object = pair
-      io.write(" " * level) unless i == 0
-      io.write "-"
-      members.output( io , key)
-      io.write( " " )
-      members.output( io , object)
-      io.write("\n")
+    node = Sof::NodeList.new(nil)
+    each do |key , object|
+      k = key.to_sof() + ": "
+      v = members.to_sof_node( object )
     end
   end
 end
diff --git a/lib/sof/node.rb b/lib/sof/node.rb
index df6b4d65..059ebf58 100644
--- a/lib/sof/node.rb
+++ b/lib/sof/node.rb
@@ -1,7 +1,15 @@
 # We transform objects into a tree of nodes
 
 module Sof
+  #abstract base class for nodes in the tree
   class Node
+    # must be able to output to a stream
+    def out io ,level
+      raise "abstract #{self}"
+    end
+  end
+  
+  class SimpleNode < Node
     def initialize head
       @head = head
     end
@@ -11,20 +19,18 @@ module Sof
     end
   end
   
-  class ChildrenNode < Node
-    def initialize head
-      super(head)
+  class NodeList < Node
+    def initialize
       @children = []
     end
     attr_accessor  :children
 
     def add child
-      child = Node.new(child) if(child.is_a? String)
+      child = SimpleNode.new(child) if(child.is_a? String)
       @children << child
     end
 
     def out io , level = 0
-      super
       return if @children.empty?
       first = @children.first
       io.write "-"
diff --git a/lib/sof/writer.rb b/lib/sof/writer.rb
index a7b42523..6cd9e007 100644
--- a/lib/sof/writer.rb
+++ b/lib/sof/writer.rb
@@ -14,7 +14,7 @@ module Sof
 
     def to_sof_node(object)
       if is_value?(object)
-        return Node.new(object.to_sof())
+        return SimpleNode.new(object.to_sof())
       end
       occurence = @members.objects[object]
       raise "no object #{object}" unless occurence
@@ -31,7 +31,7 @@ module Sof
       immediate , extended = attributes.partition {|a| is_value?(get_value(object , a) ) }
       head += immediate.collect {|a| "#{a}: #{get_value(object , a).to_sof()}"}.join(", ") + ")"
 
-      node = Node.new(head)
+      node = SimpleNode.new(head)
       extended.each do |a|
         val = get_value(object , a)
         node.add to_sof_node(val)
diff --git a/test/sof.rb b/test/sof.rb
index 4e72235d..4607b777 100644
--- a/test/sof.rb
+++ b/test/sof.rb
@@ -42,13 +42,13 @@ class BasicSof < MiniTest::Test
     out = Sof::Writer.write([true, 1 , [true , 12 , [true , 123 ]]])
     assert_equal "-true\n-1\n--true\n -12\n --true\n  -123" , out
   end
-  def ttest_array_array_object
+  def test_array_array_object
     out = Sof::Writer.write([true, 1 , [true , 12 , ObjectWithAttributes.new]])
-    puts out
-    assert_equal "-true\n-1\n--true\n -12\n -#{OBJECT_STRING}\n\n" , out
+    assert_equal "-true\n-1\n--true\n -12\n -#{OBJECT_STRING}" , out
   end
   def ttest_simple_hash
     out = Sof::Writer.write({ one: 1 , tru: true })
+    puts out
     assert_equal "-:one 1\n-:tru true\n" , out
   end
   def ttest_hash_object