if there's no "if shared_param.grad is not None:    return" what will happen?

```
        if shared_param.grad is not None:
            return
        shared_param._grad = param.grad
```
in this code, if there's no `if shared_param.grad is not None:
            return` shared_param._grad will be assigned each time? maybe just some performance loss?
maybe a stupid question, but i'm curious, thanks in advance.