From a85eceff3b29675b1e4a410974579acf35143f82 Mon Sep 17 00:00:00 2001
From: Ryan Dwyer <ryanpdwyer@gmail.com>
Date: Tue, 13 Jan 2015 15:30:18 -0500
Subject: [PATCH] Switched to tuple for python 2.6 compatibility

---
 pint/util.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pint/util.py b/pint/util.py
index 647defa..9851c68 100644
--- a/pint/util.py
+++ b/pint/util.py
@@ -623,7 +623,7 @@ def to_units_container(unit_like, registry=None):
     elif dict in mro:
         return UnitsContainer(unit_like)
 
-_prefixes = {'atto',
+_prefixes = ('atto',
             'exa',
             'femto',
             'giga',
@@ -650,7 +650,7 @@ _prefixes = {'atto',
             'pebi',
             'exbi',
             'zebi',
-            'yobi'}
+            'yobi')
 
 _prefixes_regex = '^('+'|'.join(_prefixes)+')+'
 _find_prefixes = re.compile(_prefixes_regex)