Question: Rationale for result.nonces_after.len() == 1 restriction in process_simulation_task_result

What is the purpose of the constraint result.nonces_after.len() == 1 in simtree.process_simulation_task_result?
```
// we don't really need state here because nonces are cached but its smaller if we reuse pending state fn
fn process_simulation_task_result(
&mut self,
result: SimulatedResult,
state: &NonceCacheRef,
) -> Result<(), ProviderError> {
self.sims.insert(result.id, result.clone());
let mut orders_ready = Vec::new();
if result.nonces_after.len() == 1 {
...

```