title: Using `@unittest.skipIf` with older versions of Python
body: <p>With the <code>unittest</code> module, I like the <a href="http://docs.python.org/library/unittest.html#skipping-tests-and-expected-failures">feature to skip tests</a>, but it is only available in Python 2.7+.</p>
  
  <p>For example, consider <code>test.py</code>:</p>
  
  <pre><code>import unittest
  try:
      import proprietary_module
  except ImportError:
      proprietary_module = None
  
  class TestProprietary(unittest.TestCase):
      @unittest.skipIf(proprietary_module is None, "requries proprietary module")
      def test_something_proprietary(self):
          self.assertTrue(proprietary_module is not None)
  
  if __name__ == '__main__':
      unittest.main()
  </code></pre>
  
  <p>If I try to run a test with an earlier version of Python, I get an error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "test.py", line 7, in &lt;module&gt;
      class TestProprietary(unittest.TestCase):
    File "test.py", line 8, in TestProprietary
      @unittest.skipIf(proprietary_module is None, "requries proprietary module")
  AttributeError: 'module' object has no attribute 'skipIf'
  </code></pre>
  
  <p>Is there a way to "trick" older versions of Python to ignore the unittest decorator, and to skip the test?</p>