How can we add `Vector3` as default parameter for a method? for example:

```
Void SpawnCube(Vector3 p = new Vector3(0,0,0)){...}

```

I just tried the line about I got an error:

> 
> Expression being assigned to optional parameter `p' must be a constant or default value
> 
> 
> 

I want to customise a function to spawn some `game objects` that if I did not provide the `transform.position`, it will go to `(0,0,0)`.