diff --git a/lib/parser.rb b/lib/parser.rb
index af75d6e..49b5e90 100644
--- a/lib/parser.rb
+++ b/lib/parser.rb
@@ -22,6 +22,7 @@ module Rpn
       # 1. regroup strings and programs
       regrouped_input = []
       splitted_input.each do |elt|
+        # TODO: handle buried-in-elt « and » (surround by ' ' and re-split)
         if elt[0] == '«'
           opened_programs += 1
           elt.gsub!( '«', '« ') if elt.length > 1 && elt[1] != ' '