..........F.....

======================================================================

FAIL: testLen (tester.ProblemTests)

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Traceback (most recent call last):

  File ".../test.py", line 95, in testLen

    self.assertEqual(5, len(Interval(0, 5)))

AssertionError: 5 != 6



----------------------------------------------------------------------

Ran 16 tests in 0.005s



FAILED (failures=1)