Slicing issue in TV-denoising gradient

[lesaintjerome]

The gradient function in the reconstruction/tv_denoising.py file fails due to slicing problem.

Cell In[60], line 23, in gradient(img)
     21 slice_all = [0, slice(None, -1),]
     22 for d in range(img.ndim):
---> 23     gradient[slice_all] = np.diff(img, axis=d)
     24     slice_all[0] = d + 1
     25     slice_all.insert(1, slice(None))

IndexError: only integers, slices (`:`), ellipsis (`...`), numpy.newaxis (`None`) and integer or boolean arrays are valid indices

Converting the list to a tuple gradient[tuple(slice_all)] = np.diff(x, axis=d) seems to work fine.