missing import

setup.py

@@ -2,6 +2,7 @@
 from setuptools import find_packages, setup
 
 def get_version(prefix):
+    import os
     import re
     with open(os.path.join(prefix, '__init__.py')) as fd:
         metadata = dict(re.findall("__([a-z]+)__ = '([^']+)'", fd.read()))