Does af.regions work on 3D image input?

[solarflarefx]

From the documentation it appears as though the method is designed to work in 2D only: `def regions(image, conn = CONNECTIVITY.FOUR, out_type = Dtype.f32): """ Find the connected components in the image.

Parameters
----------
image : af.Array
      - A 2 D arrayfire array representing an image.

conn : optional: af.CONNECTIVITY. default: af.CONNECTIVITY.FOUR.
      - Specifies the connectivity of the pixels.

out_type : optional: af.Dtype. default: af.Dtype.f32.
      - Specifies the type for the output.

Returns
---------

output : af.Array
       - An array where each pixel is labeled with its component number.

"""
output = Array()
safe_call(backend.get().af_regions(c_pointer(output.arr), image.arr,
                                   conn.value, out_type.value))
return output`