class_docstr: A standard interface for optimizers wrapped by the Booster.
  
  Args:
      optim (Optimizer): The optimizer to be wrapped.
code: def backward_by_grad(self, tensor: Tensor, grad: Tensor):
      torch.autograd.backward(tensor, grad)
  
imports: from typing import Union
  import torch
  import torch.nn
  from torch import Tensor
  from torch.optim import Optimizer
label_desc: Use image node_id 9 for calling the OptimizerWrapper obj's underlying member method code with example usage: obj.backward_by_grad(tensor, grad) without return types