def METHOD_NAME(self):
    counts = [[4,2],[3,6]]
    c0 = counts[0][0] * counts[1][0]
    ind = I.Indexes(counts)
    self.assertEqual(ind.length, np.sum(np.prod(counts,0)))
    self.assertEqual(len(ind.fwd_idx), 2)
    self.assertEqual(ind.fwd_idx[0], 0)
    self.assertEqual(ind.fwd_idx[1], c0)
    self.assertEqual(len(ind.rev_idx), ind.length)
    np.testing.assert_array_equal(ind.rev_idx[:c0], 0)
    np.testing.assert_array_equal(ind.rev_idx[c0:], 1)
    start = 0
    for i, count in enumerate(ind.counts.transpose()):
        hits = np.zeros(count)
        n = np.prod(count)
        hits[ind.idx[0,start:(start + n)],
             ind.idx[1,start:(start + n)]] = np.arange(np.prod(count))
        self.assertEqual(len(np.unique(hits.ravel())), n)
        start += n