## up · function

Navigate up in the path hierarchy, by going back to the first history entry
that has a shorter path than the current one. If there's none, we just shorten
the current path.

Note that going back in browser history happens asynchronously, so `route` will not be updated immediately.

**Signature:** `(stripCount?: number) => Promise<boolean>`

**Parameters:**

- `stripCount: number` (optional)

**Returns:** Like `back`: a promise resolving `true` once we've landed,
`false` when a guard vetoed the change or another navigation superseded it.