Parameters:
         * t (torch.Tensor) -- tensor representing the parameter
           to prune
     * **default_mask** (*torch.Tensor*) -- Base mask from
       previous pruning iterations, that need to be respected
       after the new mask is applied.  Same dims as "t".

  Returns:
     mask to apply to "t", of same dims as "t"

  Return type:
     mask (torch.Tensor)

  Raises:
     **IndexError** -- if "self.dim >= len(t.shape)"

prune(t, default_mask=None, importance_scores=None)
  Computes and returns a pruned version of input tensor "t"
  according to the pruning rule specified in "compute_mask()".

  Parameters:
     * **t** (*torch.Tensor*) -- tensor to prune (of same
       dimensions as "default_mask").

     * **importance_scores** (*torch.Tensor*) -- tensor of
       importance scores (of same shape as "t") used to compute
       mask for pruning "t". The values in this tensor indicate
