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

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

FAIL: testSum (tester.ProblemTests)

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Traceback (most recent call last):

  File ".../test.py", line 105, in testSum

    self.assertRaises(ValueError, Interval.__add__, Interval(7, 99), Interval(101, 200))

AssertionError: ValueError not raised



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

Ran 16 tests in 0.007s



FAILED (failures=1)