...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(-2.0, 11.0) != Interval(-4.0, 11.0)



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Ran 16 tests in 0.016s



FAILED (failures=1)