hi, I am a newer of Pytorch. In recently, I encountered a problem about the function “torch.autograd.backward”. I have read the doc about it, while I cannot know  what it means for one parameter. The doc write “The graph is differentiated using the chain rule. If any of variables are non-scalar (i.e. their data has more than one element) and require gradient, the function additionaly requires specifying grad_variables.” Could someone give me a simple example about the variable are non-scalar and how to give the grad_variables?
Thank you very much for your attention!