Change more tests to use import_module for the modules that
should cause tests to be skipped.  Also rename import_function
to the more descriptive get_attribute and add a docstring.
diff --git a/Lib/test/test_dbm.py b/Lib/test/test_dbm.py
index 0541f86..1627fff 100755
--- a/Lib/test/test_dbm.py
+++ b/Lib/test/test_dbm.py
@@ -1,6 +1,6 @@
 from test import test_support
 import unittest
-import dbm
+dbm = test_support.import_module('dbm')
 
 class DbmTestCase(unittest.TestCase):