I have a numpy array:

```
arr = numpy.arange(25 * 10 * 20)
arr.resize((25, 10, 20))

```

I want to get slice like this:

```
arr[3:6, 2:8, 7:9]

```

This works:

```
index = [slice(3, 6), slice(2, 8), slice(7, 9)]
arr[index]

```

But this doesn't:

```
>>> index = slice([3, 2, 7], [6, 8, 9])
>>> arr[index]
TypeError: slice indices must be integers or None or have an __index__ method

```

Can it be done by ONE `slice` object? Or only `list` of 3 `slice`s will work?