def test_invalid_scalar_index(adata, index):
    # https://github.com/theislab/anndata/issues/619
    with pytest.raises(IndexError, match=r".*index.* out of range\."):
        _ = adata[index]
def combinationSum(self, candidates, target):
        self.result = []
        self.dfs(candidates,0,target,[])
        return self.result