diff --git a/taxon/taxon_fetch.py b/taxon/taxon_fetch.py
index be83f5f..6f04838 100755
--- a/taxon/taxon_fetch.py
+++ b/taxon/taxon_fetch.py
@@ -17,6 +17,7 @@
            data = list(Entrez.parse(StringIO(data_xml)))
     3. pickle file was fragile. a flag file could be used to detect whether
        data is rightly dumped.
+    4. using multi-threads to accelerate fetching.
 
 '''