From 2838a0c9fd64ebccd6e541f5a69dc06357d79d87 Mon Sep 17 00:00:00 2001
From: Javier Goizueta <jgoizueta@gmail.com>
Date: Mon, 15 Feb 2016 19:57:40 +0100
Subject: [PATCH] Add contribution note

---
 CONTRIBUTING.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 0bc8a53..01fc997 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -5,6 +5,10 @@
 Try to put as little logic in the SQL extension as possible and
 just use it as a wrapper to the Python module functionality.
 
+Once a function is defined it should never change its signature in subsequent
+versions. To change a function's signature a new function with a different
+name must be created.
+
 ### Python
 
 ...