output is given as:
  self[index[i][j][k]][j][k] += src[i][j][k]  # if dim == 0
  self[i][index[i][j][k]][k] += src[i][j][k]  # if dim == 1
  self[i][j][index[i][j][k]] += src[i][j][k]  # if dim == 2

Note:
 This operation may behave nondeterministically when given tensors
 on a CUDA device. See Reproducibility for more information.

Note:
 The backward pass is implemented only for "src.shape ==
 index.shape".

Warning:
 This function is in beta and may change in the near future.

Parameters:
      * dim (int) -- the axis along which to index
  * **index** (*LongTensor*) -- the indices of elements to scatter
    and reduce.

  * **src** (*Tensor*) -- the source elements to scatter and
    reduce

  * **reduce** (*str*) -- the reduction operation to apply for
    non-unique indices (""sum"", ""prod"", ""mean"", ""amax"",
    ""amin"")

  * **include_self** (*bool*) -- whether elements from the "self"
