added support for token stream filtering and preprocessing.

--HG--
branch : trunk
diff --git a/docs/api.rst b/docs/api.rst
index e4c7a50..e16107a 100644
--- a/docs/api.rst
+++ b/docs/api.rst
@@ -590,6 +590,8 @@
 
 .. automethod:: Environment.parse
 
+.. automethod:: Environment.preprocess
+
 .. automethod:: Template.new_context
 
 .. method:: Template.root_render_func(context)