Hi,

I'm trying to compare two tensors of the same rank but different indices. For example, some thing like

```
auto T1 = ITensor(s1,prime(s1));
auto T2 = ITensor(s2,prime(s2));
//not implemented
cout<<norm(T1+ (-1*T2))<<endl;
```

Where I'd want to have `s2`

become `s1`

and `s2'`

go to `s1'`

prime and then (I assume) easily compare them using the norm. My specific use case is that these are `Site`

type indices if that helps.

Is there a way to do this efficiently?

Thanks!