diff --git a/corrlib/tools.py b/corrlib/tools.py
new file mode 100644
index 0000000..a912731
--- /dev/null
+++ b/corrlib/tools.py
@@ -0,0 +1,11 @@
+
+
+
+def str2list(s):
+    return s.split(",")
+
+def list2str(l):
+    s = l[0]
+    for it in l[1:]:
+        s += ',' + it
+    return s
\ No newline at end of file