diff --git a/libsaria/trees.py b/libsaria/trees.py
index 24337bd9..170604dd 100644
--- a/libsaria/trees.py
+++ b/libsaria/trees.py
@@ -1,5 +1,6 @@
 # Bryan Schumaker (11/06/2010)
 
+from libsaria import data
 from libsaria.path import sep
 
 class Tree(dict):
@@ -48,10 +49,19 @@ class Tree(dict):
 			child.insert(path[1:])
 
 	def lookup(self, path):
-		print self.keys(), path
-		child = self[path[0]]
+		child = self.get(path[0], None)
+		if child == None:
+			return child
 		if len(path) > 1:
 			return child.lookup(path[1:])
+		return child.keys()
+
+	def lookup_child(self, path):
+		child = self.get(path[0], None)
+		if child == None:
+			return child
+		if len(path) > 1:
+			return child.lookup_child(path[1:])
 		return child
 
 
@@ -180,3 +190,44 @@ class DLValTree(DLTree, ValTree):
 		if len(path) > 1:
 			return child.insert(path[1:], vals)
 		return child
+
+
+class PrefTree(Tree):
+	def __init__(self):
+		Tree.__init__(self)
+
+	def init_pref(self, pref, value):
+		path = pref.split('.')
+		if self.lookup(path) == None:
+			self.insert(path + [value])
+
+	def set_pref(self, pref, value):
+		path = pref.split('.')
+		child = self.lookup_child(path)
+		if child == None:
+			self.init_pref(pref, value)
+			return
+		del child[child.keys()[0]]
+		child.insert([value])
+		self.insert(path + [value])
+
+	def get_pref(self, pref):
+		path = pref.split('.')
+		val = self.lookup(path)
+		if val == None:
+			return None
+		return val[0]
+
+
+class PersPrefTree(PrefTree):
+	def __init__(self, file = None):
+		PrefTree.__init__(self)
+		self.file = file
+
+	def init_pref(self, pref, value):
+		PrefTree.init_pref(self, pref, value)
+		data.save(self.file, ".tree")
+
+	def set_pref(self, pref, value):
+		PrefTree.set_pref(self, pref, value)
+		data.save(self.file, ".tree")