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

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

FAIL: testExpand (tester.ProblemTests)

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Traceback (most recent call last):

  File ".../test.py", line 63, in testExpand

    self.assertEqual(Interval(-2, 11), i.expand(left=-1))

AssertionError: Interval(-2, 11) != Interval(-4, 11)



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

FAIL: testSum (tester.ProblemTests)

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Traceback (most recent call last):

  File ".../test.py", line 102, in testSum

    self.assertEqual(Interval(None, None), Interval(None, 11) + Interval(10, None))

AssertionError: Interval(None, None) != Interval(10, 11)



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

Ran 16 tests in 0.012s



FAILED (failures=2)