code: def _SparseSparseMaximumGrad(unused_op: ops.Operation, unused_grad):
      raise NotImplementedError(
          "Gradient for SparseSparseMaximum is not implemented."
      )
  
imports: from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import sparse_tensor
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import gen_sparse_ops
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops import sparse_ops
label_desc: Use image node_id 12 for calling a global function with example usage: _SparseSparseMaximumGrad(unused_op, unused_grad) without return types