Add missing imports.
diff --git a/Lib/test/test_gl.py b/Lib/test/test_gl.py
index be76041..c9264ee 100755
--- a/Lib/test/test_gl.py
+++ b/Lib/test/test_gl.py
@@ -3,6 +3,7 @@
     taken mostly from the documentation.
     Roger E. Masse
 """
+import unittest
 from test.test_support import verbose, import_module
 import time
 gl = import_module('gl')