new_contents: 
  import unittest
  
  from u2flib_host import exc
  
  
  class APDUErrorTest(unittest.TestCase):
      def test_init(self):
          error = exc.APDUError(0x3039)
          self.assertEqual(error.args[0], '0x3039')
          self.assertEqual(error.code, 0x3039)
          self.assertEqual(error.sw1, 0x30)
          self.assertEqual(error.sw2, 0x39)
  
subject: Add rudimentary unit test for APDUError