code: def num_outputs_per_input(self, x1, x2):
      return x1.size(-1) + 1
  
imports: from typing import Optional
  import torch
  from .polynomial_kernel import PolynomialKernel
label_desc: Use image node_id 2 for calling the PolynomialKernelGrad obj's underlying member method code with example usage: obj.num_outputs_per_input(x1, x2) and returns: unknown