we probably want to make sure that this variable is cleared after the "top most" findDiff() call, otherwise calling findDiff() twice, between two elements and then two different elements, will have the second call still containing the diff information of the first call. If you look at https://github.com/andeic/DOM-diff/blob/74394ac6e0b51d0752abfd136bf8e3ce92b84d77/domdiff.js#L185 we might be able to exploit the fact that a "top level" call will only have two arguments, with the `route` parameter actually being undefined, so we could do something like

```
var findDiff = function findDiff(t1, t2, route) {
  if (!route) {
    diff = [];
    route = [];
  }
  ...
```