code: def backward(ctx, grad_output):
      w_star, dim = ctx.saved_tensors
      return sparsemax_grad(grad_output, w_star, dim.item()), None
  
file_path: pytorch-struct/torch_struct/semirings/sparse_max.py
imports: import torch
  from .semirings import _BaseLog
label_desc: Use image node_id 2 for calling the _SparseMaxGrad obj's underlying member method code with example usage: obj.backward(ctx, grad_output) and returns: sparsemax_grad,  None