def _check___sub__(self, test, expect):
        f = FrameSet(test)
        v = [i + max(expect) + 1 for i in expect] or range(999, 1999)
        t = FrameSet.from_iterable(v)
        r = f - t
        e = FrameSet.from_iterable(set(expect) - set(v), sort=True)
        m = u'FrameSet("{0}") - FrameSet("{1}") != FrameSet("{2}")'
        self.assertEqual(r, e, m.format(f, t, e))
        m = u'FrameSet("{0}") - FrameSet("{1}") returns {2}: got {3}'
        self.assertIsInstance(r, FrameSet, m.format(test, t, FrameSet, type(r)))
Harness to test if the FrameSet.__sub__ call works properly.
dataset/ETHPy150Open sqlboy/fileseq/test/run.py/TestFrameSet._check___sub__