code: def model_grads_to_master_grads(model_params, master_params):
      """
      Copy the gradients from the model parameters into the master parameters
      from make_master_params().
      """
      master_params[0].grad = _flatten_dense_tensors(
          [param.grad.data.detach().float() for param in model_params]
      )
  
file_path: improved-diffusion/improved_diffusion/fp16_util.py
imports: import torch.nn
  from torch._utils import _flatten_dense_tensors, _unflatten_dense_tensors
label_desc: Use image node_id 4 for calling a global function with example usage: model_grads_to_master_grads(model_params, master_params) without return types