code: def backward(ctx, grad_output):
      (input,) = ctx.saved_tensors
      grad_input = grad_output.clone()
      grad_input[input < 0] = 0
      return grad_input
  
imports: import torch
label_desc: Use image node_id 2 for calling the CustomFunction obj's underlying member method code with example usage: obj.backward(ctx, grad_output) and returns: grad_input